The associations between pre-conception urinary phthalate concentrations, the serum metabolome, and live birth among women undergoing assisted reproduction

BACKGROUND

Phthalates are ubiquitous endocrine disruptors. Past studies have shown an association between higher preconception urinary concentrations of phthalate metabolites and lower fertility in women; however, the biological mechanisms remain unclear. Our exploratory study aimed to understand the metabolites and pathways associated with maternal preconception phthalate exposure and examine if any may underline the association between phthalate exposure and live birth using untargeted metabolomics.

METHODS

Participants (n = 183) were part of the Environment and Reproductive Health (EARTH) study, a prospective cohort that followed women undergoing in vitro fertilization (IVF) at the Massachusetts General Hospital Fertility Center (2005-2016). On the same day, women provided a serum sample during controlled ovarian stimulation, which was analyzed for metabolomics using liquid chromatography coupled with high-resolution mass spectrometry and two chromatography columns, and a urine sample, which was analyzed for 11 phthalate metabolites using targeted approaches. We used multivariable generalized linear models to identified metabolic features associated with urinary phthalate metabolite concentrations and live birth, followed by enriched pathway analysis. We then used a meet-in-the-middle approach to identify overlapping pathways and features.

RESULTS

Metabolic pathway enrichment analysis revealed 43 pathways in the C18 negative and 32 pathways in the HILIC positive columns that were significantly associated (p < 0.05) with at least one of the 11 urinary phthalate metabolites or molar sum of di-2-ethylhexyl phthalate metabolites. Lipid, amino acid, and carbohydrate metabolism were the most common pathways associated with phthalate exposure. Five pathways, tryptophan metabolism, tyrosine metabolism, biopterin metabolism, carnitine shuttle, and vitamin B6 metabolism, were also identified as being associated with at least one phthalate metabolite and live birth following IVF.

CONCLUSION

Our study provides further insight into the metabolites and metabolomics pathways, including amino acid, lipid, and vitamin metabolism that may underlie the observed associations between phthalate exposures and lower fertility in women.

Benzophenone-3 and ovarian reserve

OBJECTIVE

To evaluate the association between urinary benzophenone-3 concentrations and measures of ovarian reserve (OR) among women in the Environment and Reproductive Health (EARTH) Study seeking fertility treatment at Massachusetts General Hospital in Boston, Massachusetts.

DESIGN

Prospective cohort study.

METHODS

Women from the EARTH cohort contributed spot urine samples before assessment of OR outcomes. Antral follicle count (AFC) and day-3 follicle stimulating hormone (FSH) levels were evaluated as part of standard infertility workups during unstimulated menstrual cycles. Quasi-Poisson and linear regression models were used to evaluate the association of specific gravity (SG)-adjusted urinary benzophenone-3 concentrations with AFC and FSH, respectively, with adjustment for age and physical activity. In secondary analyses, models were stratified by age. Sensitivity analyses assessed for confounding by season by restricting to women with exposure and outcome measured in the same season and stratifying by summer vs. non-summer months and for confounding by sunscreen use by restricting to women who filled out product questionnaires and adjusting for and stratifying by average sunscreen use score.

RESULTS

The study included 142 women (mean age ± SD, 36.1 ± 4.6; range, 22-45 years) enrolled between 2009 and 2017 with both urinary benzophenone-3 and AFC and 57 women with benzophenone-3 and FSH measurements. Most women were white (78%) and highly educated (49% with a graduate degree). Women contributed a mean of 2.7 urine samples (range, 1-10) with 37% contributing 2 or more samples. Benzophenone-3 was detected in 98% of samples. Geometric mean (GM) SG-corrected urinary benzophenone-3 concentration was 85.9 μ g/L (geometric standard deviation 6.2). There were no associations of benzophenone-3 with AFC and day-3 FSH in the full cohort. In stratified models, a 1-unit increase in log GM benzophenone-3 was associated with AFC 0.91 (95% CI, 0.86, 0.97) times lower among women ≤35 years old and was associated with FSH 0.73 (95% CI, 0.12, 1.34) IU/L higher among women >35 years old. Effect estimates from models stratified by season and sunscreen use were null.

CONCLUSION

In main models, urinary benzophenone-3 was not associated with OR. However, younger may be vulnerable to potential effects of benzophenone-3 on AFC. Further research is warranted.

Associations of parental preconception and maternal pregnancy urinary phthalate biomarker and bisphenol-a concentrations with child eating behaviors

BACKGROUND

Eating behaviors are controlled by the neuroendocrine system. Whether endocrine disrupting chemicals have the potential to affect eating behaviors has not been widely studied in humans. We investigated whether maternal and paternal preconception and maternal pregnancy urinary phthalate biomarker and bisphenol-A (BPA) concentrations were associated with children's eating behaviors.

METHODS

We used data from mother-father-child triads in the Preconception Environmental exposure And Childhood health Effects (PEACE) Study, an ongoing prospective cohort study of children aged 6-13 years whose parent(s) previously enrolled in a fertility clinic-based prospective preconception study. We quantified urinary concentrations of 11 phthalate metabolites and BPA in parents' urine samples collected preconceptionally and during pregnancy. Parents rated children's eating behavior using the Child Eating Behavior Questionnaire (CEBQ). Using multivariable linear regression, accounting for correlation among twins, we estimated covariate-adjusted associations of urinary phthalate biomarkers and BPA concentrations with CEBQ subscale scores.

RESULTS

This analysis included 195 children (30 sets of twins), 160 mothers and 97 fathers; children were predominantly non-Hispanic white (84%) and 53% were male. Paternal and maternal preconception monobenzyl phthalate (MBzP) concentrations and maternal preconception mono-n-butyl phthalate (MnBP) were positively associated with emotional overeating, food responsiveness, and desire to drink scores in children (β's= 0.11 [95% CI: 0.01, 0.20]-0.21 [95% CI: 0.10, 0.31] per loge unit increase in phthalate biomarker concentration). Paternal preconception BPA concentrations were inversely associated with scores on food approaching scales. Maternal pregnancy MnBP, mono-isobutyl phthalate (MiBP) and MBzP concentrations were associated with increased emotional undereating scores. Maternal pregnancy monocarboxy-isononyl phthalate concentrations were related to decreased food avoiding subscale scores.

CONCLUSIONS

In this cohort, higher maternal and paternal preconception urinary concentrations of some phthalate biomarkers were associated with increased food approaching behavior scores and decreased food avoiding behavior scores, which could lead to increased adiposity in children.

Former smoking associated with epigenetic modifications in human granulosa cells among women undergoing assisted reproduction

Smoking exposure during adulthood can disrupt oocyte development in women, contributing to infertility and possibly adverse birth outcomes. Some of these effects may be reflected in epigenome profiles in granulosa cells (GCs) in human follicular fluid. We compared the epigenetic modifications throughout the genome in GCs from women who were former (N = 15) versus never smokers (N = 44) undergoing assisted reproductive technologies (ART). This study included 59 women undergoing ART. Smoking history including time since quitting was determined by questionnaire. GCs were collected during oocyte retrieval and DNA methylation (DNAm) levels were profiled using the Infinium MethylationEPIC BeadChip. We performed an epigenome-wide association study with robust linear models, regressing DNAm level at individual loci on smoking status, adjusting for age, ovarian stimulation protocol, and three surrogate variables. We performed differentially methylated regions (DMRs) analysis and over-representation analysis of the identified CpGs and corresponding gene set. 81 CpGs were differentially methylated among former smokers compared to never smokers (FDR < 0.05). We identified 2 significant DMRs (KCNQ1 and RHBDD2). The former smoking-associated genes were enriched in oxytocin signaling, adrenergic signaling in cardiomyocytes, platelet activation, axon guidance, and chemokine signaling pathway. These epigenetic variations have been associated with inflammatory responses, reproductive outcomes, cancer development, neurodevelopmental disorder, and cardiometabolic health. Secondarily, we examined the relationships between time since quitting and DNAm at significant CpGs. We observed three CpGs in negative associations with the length of quitting smoking (p < 0.05), which were cg04254052 (KCNIP1), cg22875371 (OGDHL), and cg27289628 (LOC148145), while one in positive association, which was cg13487862 (PLXNB1). As a pilot study, we demonstrated epigenetic modifications associated with former smoking in GCs. The study is informative to potential biological pathways underlying the documented association between smoking and female infertility and biomarker discovery for smoking-associated reproductive outcomes.

Women's preconception psychological stress and birth outcomes in a fertility clinic: the EARTH study

Background

The epidemiologic literature on women's perceived stress in relation to perinatal outcomes has been inconclusive and does not consider the preconception window of exposure.

Objective

To evaluate whether women's preconception perceived stress is related to live birth, gestational age, and birthweight in a cohort receiving fertility treatment.

Methods

This observational study included women seeking fertility care at the Massachusetts General Hospital (2004-2019). During preconception, women provided information on their psychological stress using the short version of the validated Perceived Stress Scale 4 (PSS-4). We used regression models to evaluate the associations of stress with live birth (N = 768 attempting to conceive) and perinatal outcomes (N = 413 live births) while adjusting for confounders. Stratified analyses by mode of conception [natural, intrauterine insemination (IUI), and IVF (in vitro fertilization)] and selected socioeconomic factors (race, education, and income) were also conducted.

Results

Higher psychological stress was negatively associated with the overall probability of live birth (adjusted RR = 0.95, 95% CI: 0.92, 0.98), particularly among women conceiving using IVF. However, we found no association between women's psychological stress and gestational age and birth weight in the overall analyses and also stratified by mode of conception. Similarly, we observed no differences in women's psychological stress with any of the measured outcomes by socioeconomic factors.

Discussion

These results highlight the importance of considering the preconception window and mode of conception when evaluating the relationship between women's preconception stress and live birth.

Paternal and maternal preconception and maternal pregnancy urinary phthalate metabolite and BPA concentrations in relation to child behavior

BACKGROUND

Epidemiologic studies on health effects of parental preconception exposures are limited despite emerging evidence from toxicological studies suggesting that such exposures, including to environmental chemicals, may affect offspring health.

OBJECTIVE

We investigated whether maternal and paternal preconception and maternal pregnancy urinary phthalate metabolite and bisphenol A (BPA) concentrations were associated with child behavior.

METHODS

We analyzed data from the Preconception Environmental exposure And Childhood health Effects (PEACE) Study, an ongoing prospective cohort study of children aged 6-11 years whose parent(s) previously enrolled in the prospective preconception Environment and Reproductive Health (EARTH) study. Using linear mixed models, we estimated covariate-adjusted associations of 11 urinary phthalate metabolite and BPA concentrations collected prior to conception and during pregnancy with Behavioral Assessment System for Children-3 (BASC-3) T-scores (higher scores indicate more problem behaviors).

RESULTS

This analysis included 134 mothers, 87 fathers and 157 children (24 sets of twins); parents were predominantly non-Hispanic white (mothers and fathers86%). Higher maternal preconception or pregnancy monobenzyl phthalate (MBzP) concentrations were related to higher mean externalizing problems T-scores in their children (β = 1.3 per 1-loge unit increase; 95 % CI: -0.2, 2.4 and β = 2.1, 95 % CI: 0.7, 3.6, respectively). Higher maternal preconception monocarboxyoctyl phthalate (MCOP) was suggested to be related to lower mean externalizing problems T-scores (β = -0.9; 95 % CI: -1.8, 0.0). Higher paternal preconception MCOP was suggestively associated with lower internalizing problems (β = -0.9; 95 %CI:-1.9, 0.1) and lower Behavioral Symptoms Index (BSI) T-scores (β = -1.3; 95 % CI: -2.1, -0.4).

CONCLUSION

In this cohort, higher maternal preconception and pregnancy MBzP were associated with worse parent-reported child behavior, while higher maternal and paternal preconception MCOP concentrations were related to lower BASC-3 scores.

Paternal and maternal preconception and maternal pregnancy urinary concentrations of parabens in relation to child behavior

BACKGROUND

Epidemiologic studies of the effects of parental preconception paraben exposures on child behavior are limited despite emerging evidence suggesting that such exposures may affect offspring neurodevelopment.

OBJECTIVE

We investigated whether maternal and paternal preconception and maternal pregnancy urinary concentrations of parabens were associated with child behavior.

METHODS

We analyzed data from the Preconception Environmental exposure And Childhood health Effects Study, an ongoing prospective cohort of children aged 6-13 years and their parents. We estimated covariate-adjusted associations of loge -transformed urinary methyl, propyl, and butyl paraben concentrations (individually using linear regression models and as a mixture using quantile g-computation) collected prior to conception and during pregnancy with Behavioral Assessment System for Children-3 and Behavior Rating Inventory of Executive Function T-scores (higher scores indicate more problem behaviors).

RESULTS

This analysis included 140 mothers, 81 fathers, and 171 children (25 sets of twins); parents were predominantly non-Hispanic white (88% for both mothers and fathers). In single paraben models, higher paternal preconception urinary propyl and methyl paraben concentrations were associated with higher Internalizing Problem T-scores (propyl parabenβ $\beta \;$ = 1.7; 95% confidence interval: 0.6, 2.8, methyl parabenβ $\beta \;$ = 2.2; 95% confidence interval: 0.5, 3.9) and higher Behavioral Symptom Index T-scores (propyl parabenβ $\beta \;$ = 1.4; 95% confidence interval: 0.3, 2.5, methyl parabenβ $\beta \;$ = 1.6; 95% confidence interval: -0.1, 3.3). Each quantile increase in the paternal mixture of three parabens was associated with a 3.4 (95% confidence interval: 0.67, 6.1) and 2.5 (95% confidence interval: 0.01, 5.0) increased internalizing problem and Behavioral Symptom Index T-scores respectively. Higher paternal preconception (β $\beta \;$ = 1.0; 95% confidence interval: 0.04, 1.9) and maternal preconception (β $\beta \;$ = 1.1 95% confidence interval: -0.1, 2.2) concentrations of propyl paraben were associated with higher Behavior Rating Inventory of Executive Function Metacognition Index T-scores in children, but the paraben mixtures was not.

CONCLUSION

In this cohort, paternal preconception urinary concentrations of propyl and methyl paraben were associated with worse parent-reported child behaviors.

Preconception Stress and Pregnancy Serum Glucose Levels Among Women Attending a Fertility Center

Context

The association between women's stress and pregnancy glucose levels remain unclear, specifically when considering the preconception period as a sensitive window of exposure.

Objective

We investigated whether preconception perceived stress was associated with glucose levels during pregnancy among women attending a fertility center (2004-2019).

Methods

Before conception, women completed a psychological stress survey using the short version of the validated Perceived Stress Scale 4 (PSS-4), and blood glucose was measured using a 50-gram glucose load test during late pregnancy as a part of screening for gestational diabetes. Linear and log-binomial regression models were used to assess associations of total PSS-4 scores with mean glucose levels and abnormal glucose levels ( ≥ 140 mg/dL), adjusting for age, body mass index, race, smoking, education, physical activity, primary infertility diagnosis, number of babies, and mode of conception.

Results

Psychological stress was positively associated with mean abnormal glucose levels. The adjusted marginal means (95% CI) of mean glucose levels for women in the first, second, and third tertiles of psychological stress were 115 (110, 119), 119 (115, 123), and 124 (119, 128), and mg/dL, respectively (P for trend = .007). Also, women in the second and third tertiles of psychological stress had 4% and 13% higher probabilities of having abnormal glucose compared with women in the first tertile of psychological stress (P trend = .01).

Conclusion

These results highlight the importance of considering preconception when evaluating the relationship between women's stress and pregnancy glucose levels.

Mixtures of urinary concentrations of phenols and phthalate biomarkers in relation to the ovarian reserve among women attending a fertility clinic

Although prior studies have found associations of the ovarian reserve with urinary concentrations of some individual phenols and phthalate metabolites, little is known about the potential associations of these chemicals as a mixture with the ovarian reserve. We investigated whether mixtures of four urinary phenols (bisphenol A, butylparaben, methylparaben, propylparaben) and eight metabolites of five phthalate diesters including di(2-ethylhexyl) phthalate were associated with markers of the ovarian reserve among 271 women attending a fertility center who enrolled in the Environment and Reproductive Health study (2004-2017). The analysis was restricted to one outcome per study participant using the earliest outcome after the last exposure assessment. Ovarian reserve markers included lower antral follicle count (AFC) defined as AFC < 7, circulating serum levels of day 3 follicle stimulating hormone (FSH) assessed by immunoassays, and diminished ovarian reserve (DOR) defined as either AFC < 7, FSH > 10 UI/L or primary infertility diagnosis of DOR. We applied Bayesian Kernel Machine Regression (BKMR) and quantile g-computation to estimate the joint associations and assess the interactions between chemical exposure biomarkers on the markers of the ovarian reserve while adjusting for confounders. Among all 271 women, 738 urine samples were collected. In quantile g-computation models, a quartile increase in the exposure biomarkers mixture was not significantly associated with lower AFC (OR = 1.10, 95 % CI = 0.52, 2.30), day 3 FSH levels (Beta = 0.30, 95 % CI = -0.32, 0.93) or DOR (OR = 1.02, 95 % CI = 0.52, 2.05). Similarly, BKMR did not show any evidence of associations between the mixture and any of the studied outcomes, or interactions between chemicals. Despite the lack of associations, these results need to be explored among women in other study cohorts.

Temporal trends in urinary concentrations of phenols, phthalate metabolites and phthalate replacements between 2000 and 2017 in Boston, MA

Endocrine disrupting chemicals (EDCs) can adversely affect human health and are ubiquitously found in everyday products. We examined temporal trends in urinary concentrations of EDCs and their replacements. Urinary concentrations of 11 environmental phenols, 15 phthalate metabolites, phthalate replacements such as two di(isononyl)cyclohexane-1,2-dicarboxylate (DINCH) metabolites, and triclocarban were quantified using isotope-dilution tandem mass spectrometry. This ecological study included 996 male and 819 female patients who were predominantly White/Caucasian (83 %) with an average age of 35 years and a BMI of 25.5 kg/m2 seeking fertility treatment in Boston, MA, USA. Patients provided a total of 6483 urine samples (median = 2, range = 1-30 samples per patient) between 2000 and 2017. Over the study period, we observed significant decreases (% per year) in urinary concentrations of traditional phenols, parabens, and phthalates such as bisphenol A (β: -6.3, 95 % CI: -7.2, -5.4), benzophenone-3 (β: -6.5, 95 % CI: -1.1, -18.9), parabens ((β range:-5.4 to -14.2), triclosan (β: -18.8, 95 % CI: -24, -13.6), dichlorophenols (2.4-dichlorophenol β: -6.6, 95 % CI: -8.8, -4.3); 2,5-dichlorophenol β: -13.6, 95 % CI: -17, -10.3), di(2-ethylhexyl) phthalate metabolites (β range: -11.9 to -22.0), and other phthalate metabolites including mono-ethyl, mono-n-butyl, and mono-methyl phthalate (β range: -0.3 to -11.5). In contrast, we found significant increases in urinary concentrations of environmental phenol replacements including bisphenol S (β: 3.9, 95 % CI: 2.7, 7.6) and bisphenol F (β: 6, 95 % CI: 1.8, 10.3), DINCH metabolites (cyclohexane-1,2-dicarboxylic acid monohydroxy isononyl ester [MHiNCH] β: 20, 95 % CI: 17.8, 22.2; monocarboxyisooctyl phthalate [MCOCH] β: 16.2, 95 % CI: 14, 18.4), and newer phthalate replacements such as mono-3-carboxypropyl phthalate, monobenzyl phthalate, mono-2-ethyl-5-carboxypentyl phthalate and di-isobutyl phthalate metabolites (β range = 5.3 to 45.1), over time. Urinary MHBP concentrations remained stable over the study period. While the majority of biomarkers measured declined over time, concentrations of several increased, particularly replacement chemicals that are studied.

Serum and follicular fluid metabolome and markers of ovarian stimulation

STUDY QUESTION

What metabolic pathways and metabolites in the serum and follicular fluid are associated with peak estradiol levels and the number of mature oocytes?

SUMMARY ANSWER

In the serum metabolome, mostly fatty acid and amino acid pathways were associated with estradiol levels and mature oocytes while in the follicular fluid metabolome, mostly lipid, vitamin, and hormone pathways were associated with peak estradiol levels and mature oocytes.

WHAT IS KNOWN ALREADY

Metabolomics has identified several metabolic pathways and metabolites associated with infertility but limited data are available for ovarian stimulation outcomes.

STUDY DESIGN, SIZE, DURATION

A prospective cohort study of women undergoing IVF from 2009 to 2015.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 125 women undergoing a fresh IVF cycle at a fertility clinic in the Northeast United States who provided a serum and follicular fluid sample. Untargeted metabolomics profiling was conducted using liquid chromatography with high-resolution mass spectrometry in two chromatography columns (C18 and hydrophilic interaction chromatography (HILIC)). The main ovarian stimulation outcomes were peak serum estradiol levels and number of mature oocytes. We utilized adjusted generalized linear regression models to identify significant metabolic features. Models were adjusted for age,BMI, initial infertility diagnosis, and ovarian stimulation protocol. We then conducted pathway analysis using mummichog and metabolite annotation using level-1 evidence.

MAIN RESULTS AND ROLE OF CHANCE

In the serum metabolome, 480 and 850 features were associated with peak estradiol levels in the C18 and HILIC columns, respectively. Additionally, 437 and 538 features were associated with mature oocytes in the C18 and HILIC columns, respectively. In the follicular fluid metabolome, 752 and 929 features were associated with peak estradiol levels in the C18 and HILIC columns, respectively, Additionally, 993 and 986 features were associated with mature oocytes in the C18 and HILIC columns, respectively. The most common pathways associated with peak estradiol included fatty acids (serum and follicular fluid), hormone (follicular fluid), and lipid pathways (follicular fluid). The most common pathways associated with the number of mature oocytes retrieved included amino acids (serum), fatty acids (serum and follicular fluid), hormone (follicular fluid), and vitamin pathways(follicular fluid). The vitamin D3 pathway had the strongest association with both ovarian stimulation outcomes in the follicularfluid. Four and nine metabolites were identified using level-1 evidence (validated identification) in the serum and follicular fluid metabolomes, respectively.

LIMITATIONS, REASONS FOR CAUTION

Our sample was majority White and highly educated and may not be generalizable to thewider population. Additionally, residual confounding is possible and the flushing medium used in the follicular fluid could have diluted our results.

WIDER IMPLICATIONS OF THE FINDINGS

The pathways and metabolites identified by our study provide novel insights into the biologicalmechanisms in the serum and follicular fluid that may underlie follicular and oocyte development, which could potentially be used to improve ovarian stimulation outcomes.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the following grants from the National Institute of Environmental Health Sciences (P30-ES019776, R01-ES009718, R01-ES022955, P30-ES000002, R00-ES026648, and T32-ES012870), and National Institute of Diabetes and Digestive and Kidney Diseases (P30DK046200). The authors have no competing interests to disclose.

TRIAL REGISTRATION NUMBER

N/A.

Associations of Maternal Urinary Concentrations of Phenols, Individually and as a Mixture, with Serum Biomarkers of Thyroid Function and Autoimmunity: Results from the EARTH Study

The associations between urinary phenol concentrations and markers of thyroid function and autoimmunity among potentially susceptible subgroups, such as subfertile women, have been understudied, especially when considering chemical mixtures. We evaluated cross-sectional associations of urinary phenol concentrations, individually and as a mixture, with serum markers of thyroid function and autoimmunity. We included 339 women attending a fertility center who provided one spot urine and one blood sample at enrollment (2009-2015). We quantified four phenols in urine using isotope dilution high-performance liquid chromatography-tandem mass spectrometry, and biomarkers of thyroid function (thyroid-stimulating hormone (TSH), free and total thyroxine (fT4, TT4), and triiodothyronine (fT3, TT3)), and autoimmunity (thyroid peroxidase (TPO) and thyroglobulin (Tg) antibodies (Ab)) in serum using electrochemoluminescence assays. We fit linear and additive models to investigate the association between urinary phenols-both individually and as a mixture-and serum thyroid function and autoimmunity, adjusted for confounders. As a sensitivity analysis, we also applied Bayesian Kernel Machine Regression (BKMR) to investigate non-linear and non-additive interactions. Urinary bisphenol A was associated with thyroid function, in particular, fT3 (mean difference for a 1 log unit increase in concentration: -0.088; 95% CI [-0.151, -0.025]) and TT3 (-0.066; 95% CI [-0.112, -0.020]). Urinary methylparaben and triclosan were also associated with several thyroid hormones. The overall mixture was negatively associated with serum fT3 concentrations (mean difference comparing all four mixture components at their 75th vs. 25th percentiles: -0.19, 95% CI [-0.35, -0.03]). We found no evidence of non-linearity or interactions. These results add to the current literature on phenol exposures and thyroid function in women, suggesting that some phenols may alter the thyroid system.

Traffic-related air pollution and supplemental folic acid intake in relation to DNA methylation in granulosa cells

BACKGROUND

Higher exposure to traffic-related air pollution (TRAP) is related to lower fertility, with specific adverse effects on the ovary. Folic acid may attenuate these effects. Our goal was to explore the relation of TRAP exposure and supplemental folic acid intake with epigenetic aging and CpG-specific DNA methylation (DNAm) in granulosa cells (GC). Our study included 61 women undergoing ovarian stimulation at a fertility center (2005-2015). DNAm levels were profiled in GC using the Infinium MethylationEPIC BeadChip. TRAP was defined using a spatiotemporal model to estimate residence-based nitrogen dioxide (NO2) exposure. Supplemental folic acid intake was measured with a validated food frequency questionnaire. We used linear regression to evaluate whether NO2 or supplemental folic acid was associated with epigenetic age acceleration according to the Pan-tissue, mural GC, and GrimAge clocks or DNAm across the genome adjusting for potential confounders and accounting for multiple testing with a false discovery rate < 0.1.

RESULTS

There were no associations between NO2 or supplemental folic acid intake and epigenetic age acceleration of GC. NO2 and supplemental folic acid were associated with 9 and 11 differentially methylated CpG sites. Among these CpGs, only cg07287107 exhibited a significant interaction (p-value = 0.037). In women with low supplemental folic acid, high NO2 exposure was associated with 1.7% higher DNAm. There was no association between NO2 and DNAm in women with high supplemental folic acid. The genes annotated to the top 250 NO2-associated CpGs were enriched for carbohydrate and protein metabolism, postsynaptic potential and dendrite development, and membrane components and exocytosis. The genes annotated to the top 250 supplemental folic acid-associated CpGs were enriched for estrous cycle, learning, cognition, synaptic organization and transmission, and size and composition of neuronal cell bodies.

CONCLUSIONS

We found no associations between NO2, supplemental folic acid, and DNAm age acceleration of GC. However, there were 20 differentially methylated CpGs and multiple enriched GO terms associated with both exposures suggesting that differences in GC DNAm could be a plausible mechanism underlying the effects of TRAP and supplemental folic acid on ovarian function.

Occupational factors and markers of testicular function among men attending a fertility center

STUDY QUESTION

Are occupational factors associated with markers of testicular function among men attending a fertility center?

SUMMARY ANSWER

Men working non-daytime/rotating shifts and those with physically demanding jobs have higher sperm concentration and total sperm count as well as higher estradiol and total testosterone concentrations.

WHAT IS KNOWN ALREADY

Semen quality has declined during recent decades and has been negatively correlated with higher risks of common chronic diseases and mortality, highlighting its public health importance beyond fertility and reproduction. While most of the previous epidemiology literature on male fertility has focused on environmental exposures, dietary factors, and other related variables, little attention has been paid to occupational factors.

STUDY DESIGN, SIZE, DURATION

This observational study included 377 men who were male partners in couples seeking infertility treatment at a fertility center, who enrolled in the Environment and Reproductive Health (EARTH) study between 2005 and 2019.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Self-reported information on lifting/moving heavy objects, typical shift, and physical level of exertion at work was collected from a take-home questionnaire. Semen samples were analyzed following World Health Organization guidelines. Enzyme immunoassays were used to assess reproductive hormone concentrations. Linear regression models were used to evaluate the association between occupational factors and measures of testicular function, while adjusting for covariates such as age, BMI, education, race, smoking, and abstinence time, and accounting for multiple semen samples (mean = 2, min-max = 1-9) in analyses for semen parameters.

MAIN RESULTS AND THE ROLE OF CHANCE

Men had a median (interquartile range) age of 36 (33, 39) years and were predominantly Caucasian (87%). Of the men who completed the survey, 12% reported often lifting or moving heavy objects at work, 6% reported heavy physical exertion at work, and 9% reported evening or rotating shifts. Men who reported often lifting or moving heavy objects at work had 46% higher sperm concentrations (P = 0.01) and 44% higher total counts (P = 0.01) compared with men who reported never lifting or moving heavy objects at work. Similar results were found for men working in rotating shifts compared to those in day shifts, as well as for men involved in heavy levels of physical exertion compared to those with light levels at work. We also found that men involved in heavy/moderate levels of physical exertion at work had higher circulating testosterone concentrations compared to those with lighter exertion (adjusted means of 515 and 427 ng/dl, respectively, P = 0.08), and men who often moved/lifted heavy objects at work had higher estradiol concentrations, compared to those who never did (adjusted means of 36.8 and 27.1 pg/ml, respectively, P = 0.07). Men working evening/rotating shifts had 24% higher testosterone (P = 0.04) and 45% higher estradiol concentrations (P = 0.01), compared to men working day shifts. No associations were observed for ejaculated volume, total motility, morphologically normal sperm, or serum FSH and LH concentrations.

LIMITATIONS, REASONS FOR CAUTION

Due to our study design which recruited men from couples seeking fertility treatment, it may not be possible to generalize our findings to men from the general population. Also, as is the case of all studies based on self-reported questionnaires, measurement error and misclassification of the exposure are potential concerns.

WIDER IMPLICATIONS OF THE FINDINGS

Physically demanding jobs and rotating or evening shift occupations may be associated with higher testicular function in men measured as higher sperm concentrations and counts as well as higher serum testosterone and estradiol levels. Confirmation of these findings in other non-fertility clinic study populations is warranted.

STUDY FUNDING/COMPETING INTEREST(S)

NIH grants R01ES022955, R01ES009718, R01ES033651, and R01ES000002 from the National Institute of Environmental Health Sciences (NIEHS) and Legacy, Inc. R.A.G. works part time for Legacy, Inc., which provided funds to perform this analysis. There are no other conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Perceived stress and markers of ovarian reserve among subfertile women

RESEARCH QUESTION

Is self-reported psychological stress associated with markers of ovarian reserve among subfertile women?

DESIGN

Observational study of women (n = 520) seeking fertility care at the Massachusetts General Hospital who enrolled in the Environment and Reproductive Health study between 2005 and 2019. Women completed the short version of the validated PSS4, which assesses psychological stress. Ovarian reserve markers included AFC and circulating serum levels of day-3 FSH, with AMH assessed in a subset of participants (n = 185).

RESULTS

Higher total PSS4 scores were negatively associated with AFC and serum AMH levels. Analyses adjusted for age, BMI, race, smoking, education, physical activity and type of infertility diagnosis. Women in the second and third tertiles of stress had lower AFC (13.3, 95% CI 12.7 to 13.8; and 13.5, 95% CI 13.0 to 14.1) compared with women in the lowest tertile of psychological stress score (14.3, 95% CI 13.8 to 14.9, both P < 0.05). Women in the second and third tertiles of total PSS4 scores also had lower mean serum AMH compared with women in the lowest tertile (2.99, 95% CI 2.24 to 3.74), and (2.99 95% CI 2.22 to 3.76) versus (3.94 95% CI 3.23 to 4.64). These associations varied by several socioeconomic factors, and were observed among women who were younger, belonging to minority races, with a college degree or with annual household income less than $100,000.

CONCLUSIONS

Higher perceived stress was negatively associated with AFC and serum AMH levels. These associations varied by several socioeconomic factors.

Phthalates impact on the epigenetic factors contributed specifically by the father at fertilization

BACKGROUND

Preconception exposure to phthalates such as the anti-androgenic dibutyl-phthalate (DBP) impacts both male and female reproduction, yet how this occurs largely remains unknown. Previously we defined a series of RNAs expressly provided by sperm at fertilization and separately, and in parallel, those that responded to high DBP exposure. Utilizing both populations of RNAs, we now begin to unravel the impact of high-DBP exposure on those RNAs specifically delivered by the father.

RESULTS

Enrichment of RNAs altered by DBP exposure within the Molecular Signature Database highlighted cellular stress, cell cycle, apoptosis, DNA damage response, and gene regulation pathways. Overlap within each of these five pathways identified those RNAs that were specifically (≥ fivefold enriched) or primarily (≥ twofold enriched) provided as part of the paternal contribution compared to the oocyte at fertilization. Key RNAs consistently altered by DBP, including CAMTA2 and PSME4, were delivered by sperm reflective of these pathways. The majority (64/103) of overlapping enriched gene sets were related to gene regulation. Many of these RNAs (45 RNAs) corresponded to key interconnected CRREWs (Chromatin remodeler cofactors, RNA interactors, Readers, Erasers, and Writers). Modeling suggests that CUL2, PHF10, and SMARCC1 may coordinate and mechanistically modulate the phthalate response.

CONCLUSIONS

Mediated through a CRREW regulatory network, the cell responded to exposure presenting stressed-induced changes in the cell cycle-DNA damage-apoptosis. Interestingly, the majority of these DBP-responsive epigenetic mediators' direct acetylation or deacetylation, impacting the sperm's cargo delivered at fertilization and that of the embryo.

Self-reported history of comorbidities and markers of ovarian reserve among subfertile women

PURPOSE

To investigate whether history of comorbidities is associated with markers of ovarian reserve among subfertile women.

METHODS

This observational study includes 645 women seeking fertility care at the Massachusetts General Hospital who enrolled in the Environment and Reproductive Health (EARTH) study (2005-2019). Women completed a comprehensive questionnaire including medical diagnosis of comorbidities. Ovarian reserve markers including antral follicle count (AFC), assessed by transvaginal ultrasound, and circulating serum levels of day 3 FSH and AMH, are assessed by immunoassays. We fit linear regression models to evaluate the association between history of comorbidities and markers of ovarian reserve while adjusting for confounders.

RESULTS

Self-reported history of hypertension, cancer, and neurological disorders was negatively associated with AFC in unadjusted models and in adjusted models for age, smoking, physical activity, comorbidity count, and BMI. Adjusted mean AFC (95% CI) was lower among women with history of hypertension, compared to women with no self-reported history of hypertension (11.5 vs 15.6, p value 0.0001). In contrast, day 3 FSH levels were positively related to history of eating disorders in both unadjusted and adjusted models (10.8 vs. 7.43 IU/L, p value ≤ 0.0001). Self-reported history of other comorbidities was unrelated to AFC, day 3 FSH, and AMH levels.

CONCLUSIONS

History of hypertension, cancer, and neurological disorders was negatively associated with AFC, and eating disorders were positively related to day 3 FSH levels. The prevention of common comorbidities among women in reproductive age may help increase women's fertility given the declining birth rates and increasing use of assisted reproductive technologies in the past years.

Pregnancy urinary concentrations of bisphenol A, parabens and other phenols in relation to serum levels of lipid biomarkers: Results from the EARTH study

The epidemiologic literature on associations between urinary phenol concentrations and lipid profiles during pregnancy is limited. We examined whether urinary concentrations of phenol and phenol replacement biomarkers were associated with serum lipid levels among pregnant women. This cross-sectional study included 175 women attending the Massachusetts General Hospital Fertility Center who enrolled in the Environment and Reproductive Health (EARTH) Study between 2005 and 2017 and had data available on urinary phenol biomarkers and serum lipids during pregnancy. We used linear regression models to assess the relationship between groups of urinary phenol and phenol replacement biomarkers and serum lipid levels [total cholesterol, high density lipoprotein (HDL), non-HDL, low-density lipoprotein (LDL) cholesterol, and triglycerides], while adjusting for age at sample collection, pre-pregnancy BMI, education, race, infertility diagnosis, cycle type, number of fetuses, trimester and specific gravity. In adjusted models, pregnant women with urinary propylparaben concentrations in the highest tertile had 10% [22 (95% CI = 5, 40) mg/dL], 12% [19 (95% CI = 2, 36) mg/dL] and 16% [19 (95% CI = 3, 35) mg/dL] higher mean total, non-HDL and LDL cholesterol, respectively, compared to women with concentrations in the lowest tertile. Similar elevations were observed for urinary bisphenol A concentrations. Urinary bisphenol S, benzophenone-3, triclosan, methylparaben, ethylparaben, and butylparaben were unrelated to serum lipids. Among pregnant women, urinary concentrations of bisphenol A and propylparaben were associated with higher serum levels of total, non-HDL and LDL cholesterol.

Paternal adherence to healthy dietary patterns in relation to sperm parameters and outcomes of assisted reproductive technologies

OBJECTIVE

To investigate whether men's adherence to dietary patterns promoted for the prevention of cardiovascular disease is associated with semen parameters and couples' assisted reproductive technology (ART) outcomes.

DESIGN

Prospective cohort study.

SETTING

Fertility center at an academic medical center.

PATIENT(S)

A total of 245 men and their female partners who underwent 438 ART cycles between 2007 and 2020.

INTERVENTION(S)

Male pretreatment dietary intake was assessed with a 131-item food frequency questionnaire from which we calculated eight a priori defined scores: Trichopoulou Mediterranean, Alternate Mediterranean, Panagiotakos Mediterranean, Healthy Eating Index, Alternative Healthy Eating Index, American Heart Association, Dietary Approaches to Stop Hypertension, and Plant-based.

MAIN OUTCOME MEASURE(S)

The primary outcome was live births per treatment cycle. The secondary outcomes were fertilization, implantation, and clinical pregnancy and seminogram parameters.

RESULT(S)

There was an inverse association between greater adherence by men to the Panagiotakos Mediterranean diet and the American Heart Association dietary pattern and lower fertilization rate. However, there were no significant associations between men's adherence to any of the analyzed dietary patterns and the probabilities of implantation, clinical pregnancy, or live birth in multivariable-adjusted models. No significant differences in any of the semen parameters were found between participants of the lowest quartile and those of the highest quartile of the eight dietary patterns.

CONCLUSION(S)

These findings suggest that men's adherence to several a priori defined dietary scores with documented cardiovascular benefits is not related to major outcomes of infertility treatment with ART or semen quality.

Folate intake and ovarian reserve among women attending a fertility center

OBJECTIVE

To examine the association between dietary folate intake and antral follicle count (AFC) among women seeing treatment for infertility.

DESIGN

Cohort study.

SETTING

Academic fertility center.

PATIENTS

A total of 552 women attending the Massachusetts General Hospital Fertility Center (2007-2019) who participated in the Environment and Reproductive Health Study.

INTERVENTIONS

None. Folate intake was measured with a validated food frequency questionnaire at study entry. Multivariable Poisson regression models with robust standard errors were used to estimate the association of folate intake with AFC adjusting for calorie intake, age, body mass index, physical activity, education, smoking status, year of AFC, and intakes of vitamin B₁₂, iron, and vitamin D. Nonlinearity was assessed with restricted cubic splines.

MAIN OUTCOME MEASURE

AFC as measured by transvaginal ultrasonography as part of routine care.

RESULTS

Among the 552 women (median age, 35.0 years; median folate intake, 1,005 μg/d), total and supplemental folate intake had a significant nonlinear relationship with AFC. There was a positive linear association with AFC up to approximately 1,200 μg/d for total folate intake and up to 800 μg/d for supplemental folate intake; however, there was no additional benefit of higher folate intakes. The magnitude of the association was modest; for example, the predicted adjusted difference in AFC between a woman consuming 400 vs. 800 μg/d of supplemental folate was approximately 1.5 follicles.

CONCLUSION

Higher intake of folate, particularly from supplements, was associated with modestly higher ovarian reserve as measured by AFC among women attending a fertility center.

CLINICAL TRIAL REGISTRATION NUMBER

This trial was registered at clinicaltrials.gov as NCT00011713.

A dietary score representing the overall relation of men's diet with semen quality in relation to outcomes of infertility treatment with assisted reproduction

Objective

To examine the impact of men's diet on outcomes of infertility treatment with assisted reproductive technology (ART) using an empirical score representing the relation of diet with semen quality.

Design

Prospective cohort study.

Setting

Fertility center at an academic medical center.

Patients

We included 296 men (688 semen samples) to identify an empirical dietary pattern and 231 couples (406 ART cycles) to investigate the association of this diet pattern with ART outcomes.

Interventions

Men's diet was assessed at baseline using a validated questionnaire. An empirical dietary pattern reflecting the overall relation of diet with semen quality was identified using reduced rank regression.

Main Outcome Measures

The primary outcome was live birth per treatment cycle. The secondary outcomes were fertilization, implantation, and clinical pregnancy.

Results

Men had a median baseline age and body mass index of 36.8 years and 26.9 kg/m², respectively. Although the empirical diet pattern was significantly associated with all semen parameters, the empirical diet score was not related to any clinical outcome of infertility treatment after ART. The adjusted probabilities of relevant clinical outcomes in the lowest and highest quartiles of the empirical score were 0.62 (0.50-0.73) and 0.55 (0.45-0.66) for implantation, 0.57 (0.46-0.69) and 0.50 (0.40-0.61) for clinical pregnancy, and 0.49 (0.37-0.62) and 0.36 (0.25-0.48) for live birth. Analyses excluding couples with a diagnosis of male factor infertility and, separately, excluding intracytoplasmic sperm injection cycles yielded similar results.

Conclusions

A dietary score representing the overall association of diet with semen quality parameters was not associated with ART outcomes.

Men's dietary patterns in relation to infertility treatment outcomes among couples undergoing in vitro fertilization

PURPOSE(S)

To evaluate the relationship of men's dietary patterns with outcomes of in vitro fertilization (IVF).

METHODS

This is a prospective cohort study including 231 couples with 407 IVF cycles, presented at an academic fertility center from April 2007 to April 2018. We assessed diet with a validated food frequency questionnaire and identified Dietary Pattern 1 and Dietary Pattern 2 using principal component analysis. We evaluated adjusted probability of IVF outcomes across the quartiles of the adherence to two dietary patterns by generalized linear mixed models.

RESULTS

Men had a median age of 36.8 years and BMI of 26.9 kg/m2. Women's median age and BMI were 35.0 years and 23.1 kg/m2, respectively. Adherence to Dietary Pattern 1 (rPearson=0.44) and Dietary Pattern 2 (rPearson=0.54) was positively correlated within couples. Adherence to Dietary Pattern 1 was positively associated with sperm concentration. A 1-unit increase in this pattern was associated with a 13.33 (0.71-25.96) million/mL higher sperm concentration. However, neither Dietary Pattern 1 nor Dietary Pattern 2 was associated with fertilization, implantation, clinical pregnancy, or live birth probabilities.

CONCLUSIONS

Data-derived dietary patterns were associated with semen quality but unrelated to the probability of successful IVF outcomes.

Hair mercury levels, intake of omega-3 fatty acids and ovarian reserve among women attending a fertility center

OBJECTIVE

To investigate the association of hair mercury (Hg) levels with antral follicle count (AFC), as a marker of ovarian reserve, and evaluate whether this relationship differed among women with high vs. low total intake of long chain omega-3 polyunsaturated fatty acids (n3PUFA) from foods and supplements.

DESIGN

We included 353 women attending an academic fertility center (2007-2019) who had data on hair Hg levels, total n3PUFA intake, and AFC.

METHODS

Hair Hg levels were assessed using a Direct Mercury Analyser, total n3PUFA intake was estimated using an extensively validated food frequency questionnaire, and AFC was assessed by transvaginal ultrasonography. Poisson regression models adjusted for potential confounders were used to evaluate the association of hair Hg levels (divided into tertiles, and as above vs below EPA reference (1 ppm)) with AFC. Associations were also evaluated after stratification by median n3PUFA intake (≤0.124% vs. >0.125% calories/week).

RESULTS

Women's median hair Hg level was 0.60 ppm (range = 0.001-8.60 ppm), with more than 30% > 1 ppm (EPA reference level). Hair Hg was positively related to AFC after adjusting for age, BMI, smoking status, infertility diagnosis, and alcohol intake. However, associations became attenuated after adjustment for intake of total n3PUFA. The positive associations of hair Hg and AFC were observed only among women above the median total n3PUFA intake. Specifically, women who consumed >0.125% calories/week of total n3PUFA had mean AFCs of 11.9, 13.2 and 14.1, respectively, across increasing tertiles of hair Hg (p,trend = 0.004). Similar results were found when hair Hg was divided above vs below EPA reference (mean AFC = 12.7 vs. 14.1, p = 0.008).

CONCLUSIONS

In these women, positive associations of hair Hg with AFC may be reflective of beneficial effects of n3PUFA on ovarian reserve rather than a beneficial effect of Hg per se. Our findings highlight the importance of considering diet when exploring Hg effects on women's reproductive health in urban settings.

Exploring reproductive associations of serum polybrominated diphenyl ether and hydroxylated brominated diphenyl ether concentrations among women undergoing in vitro fertilization

STUDY QUESTION

Are serum concentrations of polybrominated diphenyl ethers (PBDEs) and hydroxylated brominated diphenyl ethers (OH-BDEs) associated with IVF endpoints?

SUMMARY ANSWER

Positive associations were observed for BDE153 and several OH-BDEs with IVF endpoints.

WHAT IS KNOWN ALREADY

PBDEs have been voluntarily phased out of production in the USA and EU due to their persistence and toxicity to humans and ecosystems. PBDEs have been associated with implantation failure among women undergoing IVF, yet some animal studies suggest greater toxicity from their metabolites, OH-BDEs.

STUDY DESIGN, SIZE, DURATION

We evaluated a subset of 215 women (contributing 330 IVF cycles) enrolled between 2005 and 2016 in a longitudinal cohort based at Massachusetts General Hospital Fertility Center.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The following PBDEs were quantified: 47, 99, 100, 153 and 154 and the following OH-BDEs: 3-OH-BDE47, 5-OH-BDE47, 6-OH-BDE47 and 4-OH-BDE49. Clinical endpoints of IVF treatments were abstracted from electronic medical records. Associations of log-transformed PBDEs and OH-BDEs with IVF outcomes were assessed using multivariable generalized mixed models and cluster weighted generalized estimating equation models adjusted for lipids, age, BMI, race, year of sample collection, IVF protocol and FSH levels. Outcomes were adjusted to represent a percent change in outcome with an increase equal to the magnitude of the difference between the 75th and 25th percentiles for each specific compound (interquartile range (IQR) increase).

MAIN RESULTS AND THE ROLE OF CHANCE

Detection frequencies were highest for congeners 47 and 153 (82% ≥ method detection limit (MDL)) and metabolites 3 and 5-OH-BDE47 and 4-OH-BDE49 (92% > MDL). PBDE and OH-BDE geometric mean concentrations declined by up to 80% between participants recruited in 2005 and those recruited in 2016. An IQR increase of BDE153 was associated with an increase in the probability of implantation (relative risk (RR) = 1.26, 95% CI: 1.16, 1.36), clinical pregnancy (RR = 1.32, 95% CI: 1.19, 1.46) and live birth (RR = 1.34; 95% CI: 1.15, 1.54). An IQR increase in 3 and 5-OH-BDE47 was associated with increased probabilities of implantation (RR = 1.52; 95% CI: 1.11, 2.09), clinical pregnancy (RR = 1.66; 95% CI: 1.17, 2.36), and live birth (RR = 1.61; 95% CI: 1.07, 2.40). When models were stratified by race (White (86%)/Other race (14%)), associations remained positive for White women, yet inverse associations were observed for Other race women. An IQR increase in BDE47 was associated with a 46% decreased probability of clinical pregnancy (95% CI: 0.31, 0.95) for Other race women.

LIMITATIONS, REASONS FOR CAUTION

Despite the long half-lives of PBDEs and OH-BDEs, exposure misclassification is possible for women who underwent multiple treatment cycles over several months or years. It is also possible another medium, such as follicular fluid would be optimal to characterize exposure. We also tested associations for multiple congeners and metabolites with multiple outcomes.

WIDER IMPLICATIONS OF THE FINDINGS

Detections of serum concentrations of PBDEs and OH-BDEs were highest in the early years of the study and suggests that the phase-out of these compounds has contributed to a decrease in exposure. The negative associations found for PBDEs and IVF outcomes among other race women suggests the potential for racial disparity. Potential racial disparities in PBDE exposure and exploration of alternative flame retardants with reproductive health outcomes should be the focus of future investigations.

STUDY FUNDING/COMPETING INTEREST(S)

Funding for this research was supported by the National Institutes of Environmental Health Sciences (NIEHS) [R01 ES009718, ES022955, ES000002 and 009718T32ES007069]. The authors have no conflicts of interest.

Identifying windows of susceptibility to endocrine disrupting chemicals in relation to gestational weight gain among pregnant women attending a fertility clinic

BACKGROUND

Exposure to endocrine disrupting chemicals (EDC), such as phthalates and phenols, during pregnancy may be associated with excessive gestational weight gain (GWG), an important predictor of future health of the mother and the offspring. There is however a paucity of literature examining this association, and no study has accounted for the complex nature of EDCs exposure as a time-varying mixture of chemicals.

OBJECTIVE

We examined the association between trimester-specific EDCs mixture and GWG in pregnant women attending a fertility clinic, to identify windows of susceptibility to such exposures, and assess the individual contribution of each chemical over pregnancy.

METHODS

We included 243 pregnant women from the Environment and Reproductive Health (EARTH) Study, who provided up to 3 urine samples (one per trimester), and with available data on GWG. Urinary concentrations of 7 phthalate metabolites, bisphenol A, and 2 parabens, corrected for specific gravity, were included in the analysis. The association between trimester-specific EDCs mixture and GWG was evaluated using multiple regression models - categorizing exposures into concentration quartiles- and with Bayesian Kernel Machine Regression (BKMR), while adjusting for potential confounders. Hierarchical BKMR (hBKMR) was used to account for the time-varying nature of chemical concentrations over pregnancy, identifying the most important trimester and most important EDC within each trimester.

RESULTS

During 1st trimester, higher GWG was observed at higher sum of metabolites of di (2-ethylhexyl) phthalate (ΣDEHP) from both multiple regression (e.g. comparing the 4th quartile with the 1st: β = 2.36 kg, 95% CI: 0.47, 5.19) and BKMR. During 2nd and 3rd trimesters, positive associations with mono-n-butyl phthalate and propylparaben, and negative with ΣDEHP and methylparaben were observed. When evaluating exposures as a time-varying mixture with hBKMR, 1st trimester was the most important exposure window when evaluating prenatal urinary EDCs in relation to GWG. Within the 1st trimester, urinary ΣDEHP, mono-isobutyl phthalate and propylparaben had the highest contribution in the positive association between the mixture and GWG.

CONCLUSION

We observed positive associations between urinary EDCs during pregnancy, especially DEHP metabolites, and GWG. Our results suggest the 1st trimester of pregnancy as the time window of highest susceptibility to the effects of EDCs on GWG, with potential indication for the design of public health interventions, informing prevention strategies for reducing sources of exposure at specific time points.

Reproductive outcomes associated with flame retardants among couples seeking fertility treatment: A paternal perspective

BACKGROUND

Polybrominated diphenyl ethers (PBDEs) have been phased out of production for nearly a decade yet are still frequently detected in serum of U.S. adults. PBDE concentrations have been associated with adverse reproductive outcomes and laboratory studies suggest hydroxylated-BDEs (OH-BDEs) may act as endocrine disruptors. We set out to assess the joint effects of paternal and maternal serum PBDE concentrations on in vitro fertilization (IVF) outcomes and the association between paternal serum OH-BDE concentrations and IVF outcomes.

METHODS

This analysis included 189 couples (contributing 285 IVF cycles) recruited between 2006 and 2016 from a longitudinal cohort based at Massachusetts General Hospital Fertility Center who completed at least one IVF cycle and had an available blood sample at study entry. Congeners (47, 99, 100, 153, and 154) and OH-BDEs (3-OH-BDE47, 5-OH-BDE47, 6-OH-BDE47 and 4-OH-BDE49) were quantified in serum. Log-transformed PBDEs and OH-BDEs were modeled in quartiles for associations with IVF outcomes using multivariable generalized mixed models and cluster weighted generalized estimating equations.

RESULTS

Lipid-adjusted concentrations of PBDEs and OH-BDEs were higher in females than in male partners. There were no clear patterns of increases in risk of adverse IVF outcomes associated with PBDEs and OH-BDEs. However, some decreases in associations with IVF outcomes were observed in isolated quartiles.

CONCLUSIONS

Our assessment of couple level exposure is unique and highlights the importance of including male and female exposures in the assessment of the influence of environmental toxicants on pregnancy outcomes.

Paternal mixtures of urinary concentrations of phthalate metabolites, bisphenol A and parabens in relation to pregnancy outcomes among couples attending a fertility center

BACKGROUND

Few epidemiologic studies have evaluated the impact of paternal environmental exposures, particularly as mixtures, on couples' pregnancy outcomes.

OBJECTIVE

We investigated whether mixtures of paternal urinary bisphenol A (BPA), paraben, and phthalates were associated with pregnancy outcomes among couples attending a fertility center.

METHODS

We included 210 couples undergoing 300 in vitro fertilization (IVF) between 2004 and 2017 in this prospective analysis. We quantified paternal urinary biomarker concentrations in one sample per cycle using isotope-dilution tandem mass spectrometry. We used principal component analysis (PCA) to identify correlations of biomarker concentrations and multivariable Cox proportional hazards models for discrete survival time to estimate the hazard ratios (HRs) and 95% CIs for the associations between PCA-derived factor scores and probability of failing to achieve a live birth. Interactions were also included in the models to examine strength of associations over three vulnerable periods [embryo transfer to implantation, implantation to clinical pregnancy, and clinical pregnancy to live birth]. Models were adjusted for paternal and maternal ages and body mass indexes, urinary dilution (specific gravity) and year of collection, infertility diagnosis, and other PCA factor scores. Sensitivity analyses with further adjustment for maternal PCA factor scores were performed.

RESULTS

We identified three factors, representing di-2-ethylhexyl phthalate (DEHP) metabolites, BPA and non-DEHP metabolites, and parabens, accounting for 56%, 15% and 10%, respectively, of the total variance explained. An interquartile range (25th and 75th percentiles) increase in the DEHP-related factor score was associated with elevated probability of failing prior to live birth (HR = 1.41, 95% CI: 1.08, 1.81) and the association was stronger between implantation and clinical pregnancy as well as between clinical pregnancy and live birth compared to before implantation. The overall HRs of failure for the BPA/non-DEHP-related and paraben-related factor scores were HR = 1.24 (95% CI: 0.97, 1.59) and HR = 0.99 (95% CI: 0.80, 1.24). We found similar HRs when additionally adjusting for maternal PCA factor scores.

CONCLUSION

Paternal mixtures of urinary concentrations of DEHP metabolites were related to higher infertility treatment failure.

Association of personal exposure to power-frequency magnetic fields with pregnancy outcomes among women seeking fertility treatment in a longitudinal cohort study

OBJECTIVE

To assess for the first time the potential relationships of personal exposure to magnetic fields (MF) with pregnancy outcomes among a cohort of women from a fertility clinic, addressing, through study design, some of the primary limitations of previous studies on this topic.

DESIGN

Longitudinal preconception prospective cohort.

SETTING

Fertility center.

PATIENT(S)

Our analysis included 119 women recruited from 2012 to 2018, who underwent in vitro fertilization (IVF) (n = 163 cycles) and/or intrauterine insemination (IUI) (n = 123 cycles).

INTERVENTION(S)

Women wore personal exposure monitors continuously for up to three consecutive 24-hour time periods separated by several weeks.

MAIN OUTCOME MEASURE(S)

Implantation, clinical pregnancy, live birth, and pregnancy loss.

RESULT(S)

The median and maximum of the overall daily mean (daily peak) MF exposure levels were 1.10 mG (2.14 mG) and 15.54 mG (58.73 mG), respectively. MF exposure metrics were highest among women who changed environments four or more times per day. Overall, no statistically significant associations between MF exposure metrics and fertility treatment or pregnancy outcomes were observed in crude or adjusted models. Effect estimates, both positive and negative, varied by outcome and the exposure metric, including the way in which exposure was modeled.

CONCLUSION(S)

Personal MF exposures were not associated with fertility treatment outcomes or pregnancy outcomes. Despite its limited size, strengths of the study include a longitudinal repeated-measures design, the collection of personal MF exposure data across multiple days, and carefully documented outcome and covariate information among a potentially susceptible study population.

Dietary patterns and ovarian reserve among women attending a fertility clinic

OBJECTIVE

To investigate the associations between dietary patterns and antral follicle count (AFC), a marker of ovarian reserve.

DESIGN

Prospective cohort study.

SETTING

Fertility center at an academic hospital.

PATIENT(S)

A total of 363 women seeking preconception evaluation and infertility care at the Massachusetts General Hospital who participated in the Environment and Reproductive Health Study.

INTERVENTION(S)

None. At enrollment, women reported diet through a food frequency questionnaire, from which we computed three dietary pattern adherence scores: the Mediterranean diet, the Fertility diet, and the Profertility diet.

MAIN OUTCOME MEASURE(S)

The AFC was assessed with a transvaginal ultrasound performed on the third day of an unstimulated menstrual cycle or on the third day of a P withdrawal bleed.

RESULT(S)

Higher adherence to the three dietary patterns examined were unrelated to AFC. The multivariable adjusted AFC means and 95% confidence intervals for women in the highest compared with the lowest quartile of adherence score were 13.9 (13.0-14.9) and 13.5 (12.6-14.4) for the Mediterranean diet, 14.0 (13.2-14.9) and 13.5 (12.7-14.3) for the Fertility diet, and 12.5 (11.6-13.5) and 13.3 (12.5-14.2) for the Profertility diet.

CONCLUSION(S)

Dietary patterns were unrelated to AFC among a cohort of women presenting at a fertility center. Due to the limited and heterogeneous current evidence, it is important to evaluate this association in further studies, and in particular among women from the general population.

Urinary Concentrations of Phthalate Metabolite Mixtures in Relation to Serum Biomarkers of Thyroid Function and Autoimmunity among Women from a Fertility Center

BACKGROUND

Although previous epidemiological studies have explored associations of phthalate metabolites with thyroid function, no studies to date have assessed associations of mixtures with thyroid function and autoimmunity among potentially susceptible subgroups such as subfertile women.

OBJECTIVE

We aimed to explore associations of mixtures of urinary phthalate metabolites with serum markers of thyroid function and autoimmunity.

METHODS

This cross-sectional study included 558 women attending a fertility center who provided one spot urine and one blood sample at enrollment (2005-2015). We quantified urinary concentrations of eight phthalate metabolites using mass spectrometry, and biomarkers of thyroid function [thyroid-stimulating hormone (TSH), free and total thyroxine (fT4, TT4) and triiodothyronine (fT3, TT3), and autoimmunity [thyroid peroxidase and thyroglobulin antibodies (TPOAb and TgAb, respectively)] in serum using electrochemiluminescence assays. We applied principal component analysis (PCA) and Bayesian kernel machine regression (BKMR) to identify the main patterns of urinary phthalate metabolites. We used linear mixed models to assess the association between PCA-derived factor scores in quintiles and serum thyroid function and autoimmunity, adjusting for age, body mass index (BMI), specific gravity (SG), and, for the PCA, other factor scores.

RESULTS

We observed two factors using PCA, one representing the di(2-ethylhexyl) (DEHP) and another non-DEHP metabolites. Compared to women in the lowest quintile of the DEHP factor scores, women in the highest quintile had significantly lower serum concentrations of fT4, TT4, fT3, and TT3 [absolute difference: -0.62; 95% confidence interval (CI): -0.12, -0.01; p=0.04; absolute difference: -8.31; 95% CI: -13.8, -2.85; p=0.003; absolute difference: -0.37; 95% CI: 0.54, -0.19; p<0.0001; and absolute difference: -0.21; 95% CI: -0.32, -0.10; p=0.003, respectively]. Using BKMR, we observed that mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) was the primary contributor to these negative associations. DEHP and non-DEHP factor scores were not associated with serum TSH, TgAb, or TPOAb.

CONCLUSIONS

Mixtures of urinary DEHP metabolites were inversely associated with serum biomarkers of thyroid function but not with autoimmunity, which were within normal ranges for healthy adult women. https://doi.org/10.1289/EHP6740.

Perinatal urinary benzophenone-3 concentrations and glucose levels among women from a fertility clinic

BACKGROUND

Subfertile women have higher risk of glucose intolerance during pregnancy. Studies suggest associations between several endocrine disrupting chemicals (EDCs) and pregnancy glucose levels. However, the association between benzophenone-3 (BP-3), an EDC widely found in sunscreen, and pregnancy glucose levels remains unclear. We aimed to assess the association between perinatal exposures to BP-3 and pregnancy glucose levels in subfertile women.

METHODS

We evaluated 217 women from a prospective cohort based at a fertility clinic who had urinary BP-3 concentrations measured during 3-month preconception, first and/or second trimesters, and blood glucose measured at glucose load tests (GLTs) during late pregnancy. Multivariable linear and logistic regression models were used to assess associations between time-specific BP-3 in quartiles (Q1 - Q4) and mean glucose levels, as well as odds of abnormal GLT (glucose level ≥ 140 mg/dL), adjusting for potential confounders. Effect modification was assessed by age, season, BMI, infertility diagnosis, sex of fetus (es) and physical activity.

RESULTS

Women with higher first trimester BP-3 concentrations had lower mean glucose levels [mean glucose (95% CI) for Q4 vs Q1 = 103.4 (95.0, 112.5) vs. 114.6 (105.8, 124.2) mg/dL]. Women with higher second trimester BP-3 concentrations had lower odds of abnormal GLT [OR (95% CI) for Q3 vs. Q1 = 0.12 (0.01, 0.94)]. The associations between BP-3 and glucose levels were modified by several factors: women with female-factor infertility, urine collected during summer, older age, lower BMI, or carried female fetus (es) had the strongest inverse associations between BP-3 and glucose levels, while no associations were observed in the remaining subgroups.

CONCLUSIONS

Time-specific inverse associations between BP-3 and pregnancy glucose levels existed in subfertile women, and especially among certain subgroups of this high-risk-population.

Association of Parental Preconception Exposure to Phthalates and Phthalate Substitutes With Preterm Birth

IMPORTANCE

Although phthalate exposure during pregnancy has been associated with preterm birth, the association of preconception exposure in either parent with preterm birth constitutes a knowledge gap.

OBJECTIVE

To examine the association of paternal and maternal preconception urinary concentrations of biomarkers of phthalates and phthalate substitutes with singleton preterm birth.

DESIGN, SETTING, AND PARTICIPANTS

This study, conducted at an academic fertility center in Boston, Massachusetts, included a prospective preconception cohort of subfertile couples comprising 419 mothers and 229 fathers and their 420 live-born singleton offspring born between January 1, 2005, and December 31, 2018. Statistical analysis was performed from August 1 to October 31, 2019.

EXPOSURES

Urinary concentrations of metabolites of phthalates and phthalate substitutes obtained before conception.

MAIN OUTCOMES AND MEASURES

Gestational age was abstracted from delivery records and validated using the American College of Obstetricians and Gynecologists guidelines for births after medically assisted reproduction. The risk ratio (RR) of preterm birth (live birth before 37 completed weeks' gestation) was estimated in association with urinary concentrations of 11 individual phthalate metabolites, the molar sum of 4 di-(2-ethylhexyl) phthalate (ΣDEHP) metabolites, and 2 metabolites of 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH, a nonphthalate plasticizer substitute) using modified Poisson regression models adjusted for covariates.

RESULTS

The mean (SD) age of the 419 mothers was 34.7 (4.0) years, the mean (SD) age of the 229 fathers was 36.0 (4.5) years, and the mean (SD) gestational age of the 420 singleton children (217 boys) was 39.3 (1.7) weeks, with 34 (8%) born preterm. In adjusted models, maternal preconception ΣDEHP concentrations (RR, 1.50; 95% CI, 1.09-2.06; P = .01) and cyclohexane-1,2-dicarboxylic acid monohydroxy isononyl ester (MHiNCH, a metabolite of DINCH) concentrations (RR, 1.70; 95% CI, 0.89-3.24; P = .11) were associated with an increased risk of preterm birth. After additional adjustment for prenatal ΣDEHP or MHiNCH concentrations, the association of maternal preconception exposure to ΣDEHP and preterm birth remained robust (RR, 1.69; 95% CI, 1.17-2.44; P = .006), while the association of maternal preconception exposure to MHiNCH and preterm birth was attenuated (RR, 1.17; 95% CI, 0.49-2.81; P = .72). The remaining urinary metabolites examined in either parent showed no association with preterm birth.

CONCLUSIONS AND RELEVANCE

In this prospective cohort of subfertile couples, maternal preconception exposure to ΣDEHP metabolites was associated with an increased risk of preterm birth. The results suggest that female exposure to select phthalate plasticizers during the preconception period may be a potential risk factor for adverse pregnancy outcomes, which may need to be considered in preconception care strategies.

Maternal and paternal preconception exposure to phenols and preterm birth

BACKGROUND

Phenol exposure during pregnancy has been associated with preterm birth, but the potential effect of preconception exposure in either parent is unknown. There is a growing body of evidence to suggest that the preconception period is a critical window of vulnerability for adverse pregnancy outcomes.

OBJECTIVE

We examined whether maternal and paternal preconception urinary concentrations of select phenols were associated with the risk of preterm birth among couples attending fertility care.

METHODS

The analysis included 417 female and 229 male participants of the Environment and Reproductive Health (EARTH) Study who gave birth to 418 singleton infants between 2005 and 2018 and for whom we had phenol biomarkers quantified in at least one urine sample collected before conception. Mothers and fathers provided an average of 4 and 3 urine samples during the preconception period, respectively. We calculated the geometric mean of bisphenol A (BPA), bisphenol S (BPS), benzophenone-3, triclosan, and the molar sum of parabens (ΣParabens) urinary concentrations to estimate each participant's preconception exposure. Risk ratios (RRs) of preterm birth (live birth before 37 completed weeks' gestation) were estimated using modified Poisson regression models adjusted for covariates.

RESULTS

The mean (SD) gestational age among singletons was 39.3 (1.7) weeks with 8% born preterm. A natural log-unit increase in maternal preconception BPA (RR 1.94; 95% CI: 1.20, 3.14) and BPS (RR 2.42; 95% CI: 1.01, 5.77) concentration was associated with an increased risk of preterm birth. These associations remained after further adjustment for maternal prenatal and paternal preconception biomarker concentrations. Paternal preconception ΣParabens concentrations showed a possible elevated risk of preterm birth (RR 1.36; 95% CI: 0.94, 1.96). No consistent pattern of association was observed for benzophenone-3 or triclosan biomarkers in either parent.

DISCUSSION

Maternal preconception urinary BPA and BPS concentrations, as well as paternal preconception urinary parabens concentrations were prospectively associated with a higher risk of preterm birth. Subfertile couples' exposure to select phenols during the preconception period may be an unrecognized risk factor for adverse pregnancy outcomes.

Defining a study population using enhanced reporting of Aboriginality and the effects on study outcomes

Introduction

The under-reporting of Aboriginal and Torres Strait Islander people on routinely collected health datasets has important implications for understanding the health of this population. By pooling available information on individuals' Aboriginal or Torres Strait Islander status from probabilistically linked datasets, methods have been developed to adjust for this under-reporting.

Objectives

To explore different algorithms that enhance reporting of Aboriginal status in birth data to define a cohort of Aboriginal women, examine any differences between women recorded as Aboriginal and those assigned enhanced Aboriginal status, and assess the effects of using different reported populations to estimate within-group comparisons for Aboriginal people.

Methods

Three algorithms, with different levels of inclusiveness, were used to establish different study populations all of which aimed to include all singleton babies born to Aboriginal or Torres Strait Islander women residing in New South Wales, Australia between 2010 and 2014 and their mothers. The demographics of the four study populations were described and compared using frequencies and percentages. In order to assess the impact on research outcomes and conclusions of using study populations derived from different algorithms, estimates of the associations between smoking during pregnancy and selected perinatal outcomes were compared using rates and relative risks.

Results

Women included in the study population through enhanced reporting were older, less disadvantaged and more commonly resided in urban areas than those recorded as Aboriginal in the birth data. Although rates of smoking and some perinatal outcomes differed between the different study populations, the relative risks of each outcome comparing smoking and non-smoking Aboriginal mothers were very similar when estimated from each of the study populations.

Conclusions

This work provides evidence that estimates of within-group relative risks are reliable regardless of the assumptions made for establishing the study population through the enhanced reporting of indigenous peoples.

Parental preconception and prenatal urinary bisphenol A and paraben concentrations and child behavior

Epidemiologic studies suggest that prenatal urinary bisphenol A (BPA) concentrations are associated with childhood behavior problems, but there is limited research on prenatal paraben concentrations. In rodent offspring, preconception maternal BPA exposure caused behavioral problems and paraben exposure impacted sperm quality. However, the effects of parental preconception and prenatal BPA and paraben exposure on children's neurodevelopment are unknown.

METHODS

The Environment and Reproductive Health (EARTH) Study is a prospective cohort of couples from a fertility clinic at Massachusetts General Hospital. The Centers for Disease Control and Prevention (CDC) quantified BPA, butylparaben, ethylparaben, methylparaben, and propylparaben concentrations in multiple urine samples collected before conception and during pregnancy. From the eligible parents (N = 220), we enrolled 158 children between 2 and 9 years of age. The parents completed the Behavior-Assessment-System-for-Children-2 (BASC-2). We estimated covariate-adjusted associations of average parental preconception and prenatal ln-transformed urinary BPA and sum of paraben concentrations (∑paraben) with BASC-2 scores using linear regression with generalized estimating equations.

RESULTS

Median urinary BPA and Σparaben concentrations were 1.2 and 189 μg/L in mothers preconception and 1.7 and 25 μg/L in fathers preconception, respectively. Among all children, parental BPA and ∑paraben concentrations were not associated with BASC-2 behavioral symptoms index, internalizing, or externalizing problems scores. Point estimates ranged from -1.5 to 1.4 with wide 95% confidence intervals that included the null value.

CONCLUSION

In this fertility clinic cohort, parental preconception and maternal prenatal BPA and paraben concentrations were not associated with problem behaviors among children. However, our small sample sizes reduced the precision of our results.

The association of urinary phosphorous-containing flame retardant metabolites and self-reported personal care and household product use among couples seeking fertility treatment

BACKGROUND

Phosphorous-containing flame-retardants (PFRs) are widely detected. They are used both as a flame retardant as well as plasticizer.

METHODS

A subset of 230 women and 229 men were recruited from Massachusetts General Hospital fertility clinic between 2005 and 2015. At each visit, participants completed a questionnaire of personal care product (PCP) and household product (HP) use. Metabolites [bis(1,3-dichloro-2-propyl) phosphate, diphenyl phosphate (DPHP), isopropylphenyl phenyl phosphate (ip-PPP), tert-butylphenyl phenyl phosphate and bis(1-chloro-2-propyl) phosphate] were measured in urine (1-5 samples; n = 638 women, n = 335 men). Associations were assessed using generalized mixed models, adjusted for SG, age, BMI, smoking, education, and season.

RESULTS

In women, moisturizer (60%), nail polish remover (77%), and nail polish (134%) use were associated (p < 0.05) with an increase in DPHP concentrations, while ip-PPP concentrations increased 21-27% with conditioner, cosmetics, deodorant, and hair product use. Mouthwash and vinyl glove use were associated with a respective 31% and 92% increase in DPHP among men.

CONCLUSIONS

Our exploratory analysis suggests PFRs may be used as a plasticizer in consumer products, and nail polish use contributes to internal DPHP exposure. Further research is needed to understand how PFRs are used in these products and how it relates to exposure.

Association of self-reported personal care product use with blood glucose levels measured during pregnancy among women from a fertility clinic

BACKGROUND

Personal care products (PCPs), known sources of endocrine disrupting chemicals (EDCs) such as phthalates and parabens, are widely used among women of reproductive age. EDCs have been linked to pregnancy complications such as gestational diabetes (GDM), and PCP use could represent a modifiable source of exposure in this sensitive time window. Yet, to our knowledge, no study has directly evaluated the association between pregnancy use of PCP and late pregnancy glucose levels, established risk factors for complications such as GDM.

METHODS

A total of 233 women from the Environment and Reproductive Health (EARTH) Study had data available on 1st and/or 2nd trimester PCP use, assessed through self-reported use over the previous 24 h, and blood glucose levels after the glucose loading test (GLT), taken at late 2nd trimester. Associations between each individual PCP and total PCP with glucose levels were evaluated in multivariable adjusted linear regression models.

RESULTS

Both positive and negative differences in glucose levels were observed when comparing users vs. non-users of several PCPs including 2nd trimester use of deodorant (adjusted mean difference: 12.2 mg/dL, 95% CI: -0.6, 24.9); bar soap (6.9 mg/dL, 95% CI: -0.9, 14.7 mg/dL); and liquid soap (-13.3, 95% CI: -26.8, 0.1 mg/dL), and 1st trimester use of sunscreen (-14.6 mg/dL, 95% CI: -27.8, -1.5 mg/dL). Total number of PCPs used in the 2nd trimester was also associated with higher glucose levels, with the largest difference of 20 mg/dL when comparing individuals who used eight vs none PCPs (95% CI: 3-37).

CONCLUSIONS

In a pregnancy cohort of women seeking care at a fertility clinic, we found the use of several PCPs to be positively or negatively associated with glucose levels in the late second trimester, which may reflect increased risk of GDM and subsequent perinatal outcomes. These results strengthen the role of product use as a potentially modifiable source of EDCs that may impact glucose levels.

Urinary triclosan concentrations and semen quality among men from a fertility clinic

BACKGROUND

Triclosan, a widely-used antimicrobial in personal care products, has shown endocrine disrupting activity in experimental studies. However, there is limited evidence from epidemiologic studies on health effects.

OBJECTIVE

To examine the association between urinary triclosan concentrations and semen quality.

METHODS

A total of 262 men enrolled in the Environmental and Reproductive Health (EARTH) Study provided 581 paired urine and semen samples (2009-2017). Urinary triclosan concentrations were quantified and semen analysis was evaluated according to WHO guidelines. We used linear mixed regression models to estimate the associations between specific gravity-adjusted urinary triclosan concentrations with semen parameters, with a random intercept to account for multiple samples per man and adjusting for age, body mass index (BMI), smoking, physical activity, sexual abstinence time, and season and year of samples' collection.

RESULTS

Men had a mean (standard deviation) age of 36.6 (5.24) years and BMI of 27.9 (5.94) kg/m². Seventy four percent of the samples had detectable (>2.3 μg/L) concentrations. We did not observe significant dose response trends between SG-adjusted urinary triclosan concentrations and semen parameters. However, in the adjusted analysis, compared to men with non-detectable triclosan concentrations in the lowest quartile, those in the second, third, and fourth quartiles had -1.32% (95%CI: -2.04, -0.59), -0.91% (95%CI: -1.63, -0.18), and -0.46% (95%CI: -1.25, 0.33) lower percent morphologically normal sperm, respectively. Similarly, a lower percentage of morphologically normal sperm was found among men with detectable triclosan concentrations, compared to men with non-detectable triclosan [-0.96% (95% CI: -1.57, -0.35)]. In sensitivity analyses, there was stronger negative associations on the percent morphologically normal sperm in the earlier time period due to the significant negative trend in detectable triclosan concentrations over time.

CONCLUSION

Despite the lack of observed dose response relationship, we found consistent patterns of lower percent morphologically normal sperm for men with urinary triclosan in the 2nd or 3rd quartile compared to undetectable concentrations.This association was stronger for samples obtained prior to 2013 when triclosan was more often detectable in urine.

Urinary bisphenol S concentrations: Potential predictors of and associations with semen quality parameters among men attending a fertility center

BACKGROUND

Bisphenol S (BPS) was introduced in the market as a potentially safer alternative to bisphenol A (BPA). However, there are limited studies on health effects of BPS and no epidemiologic studies on its relationship with male reproductive health outcomes, specifically semen quality.

OBJECTIVE

To investigate predictors of urinary BPS concentrations and its association with semen parameters among men attending a fertility center.

METHODS

This cross-sectional analysis included 158 men of couples seeking fertility treatment (2011-2017) contributing 338 paired semen and urine samples. At the time of sample collection, men completed a questionnaire on self-reported use of household products and food intake within the previous 24 h. Urinary concentrations of BPA, BPS and bisphenol F were quantified using isotope-dilution tandem mass spectrometry. Semen samples were analyzed following WHO guidelines. Multivariable mixed models were used to investigate predictors of urinary BPS concentrations and to evaluate associations between urinary BPS concentrations and semen parameters, using random intercept to account for correlation in outcomes across multiple observations per man and adjusting for abstinence time, specific gravity, age, body mass index (BMI), year of sample collection and BPA concentrations. Analyses were also stratified by BMI (≥25 vs <25 kg/m²).

RESULTS

Median (IQR) urinary BPS concentration was 0.30 (0.20, 0.90) μg/L, and 76% of samples had detectable (>0.1 μg/L) concentrations. Self-reported fabric softener and paint/solvent use as well as intake of beef and cheese within 24 h before urine collection were positively associated with BPS concentrations. Men with higher BPS concentrations also had significantly higher BMI. Lower semen parameters were found among men with detectable BPS concentrations, compared to men with non-detectable BPS [2.66 vs. 2.91 mL for volume (p = 0.03), 30.7 vs. 38.3 mil/mL for concentration (p = 0.03), 76.8 vs. 90.0 mil for total count (p = 0.09), 43.7 vs. 47.0% for motility (p = 0.06), and 5.42 vs. 6.77% for morphologically normal sperm (p = 0.24)]. Some associations of BPS with lower semen parameters were only found among men with a BMI ≥ 25 kg/m².

CONCLUSIONS

We identified dietary and lifestyle factors associated with BPS exposure, suggesting potential avenues for reducing exposures. We also observed negative associations between BPS and semen parameters, especially among overweight and obese men.

Supplemental Folate and the Relationship Between Traffic-Related Air Pollution and Livebirth Among Women Undergoing Assisted Reproduction

Traffic-related air pollution has been linked to higher risks of infertility and miscarriage. We evaluated whether folate intake modified the relationship between air pollution and livebirth among women using assisted reproductive technology (ART). Our study included 304 women (513 cycles) presenting to a fertility center in Boston, Massachusetts (2005-2015). Diet and supplements were assessed by food frequency questionnaire. Spatiotemporal models estimated residence-based daily nitrogen dioxide (NO2), ozone, fine particulate, and black carbon concentrations in the 3 months before ART. We used generalized linear mixed models with interaction terms to evaluate whether the associations between air pollutants and livebirth were modified by folate intake, adjusting for age, body mass index, race, smoking, education, infertility diagnosis, and ART cycle year. Supplemental folate intake significantly modified the association of NO2 exposure and livebirth (P = 0.01). Among women with supplemental folate intakes of <800 μg/day, the odds of livebirth were 24% (95% confidence interval: 2, 42) lower for every 20-parts-per-billion increase in NO2 exposure. There was no association among women with intakes of ≥800 μg/day. There was no effect modification of folate on the associations between other air pollutants and livebirth. High supplemental folate intake might protect against the adverse reproductive consequences of traffic-related air pollution.

Urinary concentrations of benzophenone-3 and reproductive outcomes among women undergoing infertility treatment with assisted reproductive technologies

Benzophenone-3 is used in a variety of cosmetic products as a sunscreen, and has shown weak estrogenic and antiandrogenic activity in animal and in vitro studies. Few studies have evaluated whether benzophenone-3 is associated with reproductive outcomes among women. We studied 304 women undergoing infertility treatment (2007-2017) in the prospective Environment and Reproductive Health cohort study and who underwent 449 treatment cycles (n = 788 urines). Generalized linear mixed models were used with random intercepts to account for multiple cycles, and adjusting for confounders including physical activity. Analyses were also stratified by self-reported moderate/heavy outdoor work. The cycle-specific median (IQR) urinary benzophenone-3 concentration was 147 (58, 462) μg/L, and 98% samples had detectable concentrations. Self-reported sunscreen use, physical activity, and time spent on moderate/heavy outdoor work were positively associated with urinary benzophenone-3. Adjusted probabilities of implantation, clinical pregnancy and live birth were higher in increasing quartiles of benzophenone-3, but these associations were restricted to women who reported spending time outdoors performing moderate/heavy work. Specifically, among these women, those in the highest quartile of benzophenone-3 concentrations had 51% higher implantation (p,trend = 0.02), 68% higher clinical pregnancy (p,trend = 0.01) and 75% higher live birth (p,trend = 0.02) adjusted probabilities than women in the lowest quartile. Benzophenone-3 was unrelated to these outcomes among women who did not report doing moderate/heavy work outdoors. These results confirm that sunscreen use is a source of benzophenone-3 exposure, and show positive associations between benzophenone-3 and pregnancy outcomes, especially among women who reported engaging in outdoor work. Since these associations may be subject to important residual confounding by lifestyle factors, further research is needed to confirm these novel results in other populations, and to investigate whether other factors may be affecting the relation of benzophenone-3 with fertility and other health outcomes.

Time-Varying Exposure to Air Pollution and Outcomes of in Vitro Fertilization among Couples from a Fertility Clinic

BACKGROUND

A few studies suggest that air pollution may decrease fertility, but prospective studies and examinations of windows of susceptibility remain unclear.

OBJECTIVE

We aimed to examine the association between time-varying exposure to nitrogen dioxide ([Formula: see text]), ozone ([Formula: see text]), fine particulate matter [Formula: see text] ([Formula: see text]), and black carbon (BC) on in vitro fertilization (IVF) outcomes.

METHODS

We included 345 women (522 IVF cycles) for the [Formula: see text], [Formula: see text], and [Formula: see text] analyses and 339 women (512 IVF cycles) for the BC analysis enrolled in a prospective cohort at a Boston fertility center (2004–2015). We used validated spatiotemporal models to estimate daily residential exposure to [Formula: see text], [Formula: see text], [Formula: see text], and BC. Multivariable discrete time Cox proportional hazards models with four periods [ovarian stimulation (OS), oocyte retrieval to embryo transfer (ET), ET to implantation, implantation to live birth] estimated odds ratios (OR) and 95% confidence intervals (CI) of failing at IVF. Time-dependent interactions were used to identify vulnerable periods.

RESULTS

An interquartile range (IQR) increase in [Formula: see text], [Formula: see text], and BC throughout the IVF cycle was associated with an elevated odds of failing at IVF prior to live birth ([Formula: see text], 95% CI: 0.95, 1.23 for [Formula: see text]; [Formula: see text], 95% CI: 0.88, 1.28 for [Formula: see text]; and [Formula: see text], 95% CI: 0.96, 1.41 for BC). This relationship significantly varied across the IVF cycle such that the association with higher exposure to air pollution during OS was strongest for early IVF failures. An IQR increase in [Formula: see text], [Formula: see text], and BC exposure during OS was associated with 1.42 (95% CI: 1.20, 1.69), 1.26 (95% CI: 0.96, 1.67), and 1.23 (95% CI: 0.96, 1.59) times the odds of failing prior to oocyte retrieval, and 1.32 (95% CI: 1.13, 1.54), 1.27 (95% CI: 0.98, 1.65), and 1.32 (95% CI: 1.10, 1.59) times the odds of failing prior to ET.

CONCLUSION

Increased exposure to traffic-related pollutants was associated with higher odds of early IVF failure. https://doi.org/10.1289/EHP4601.

Waist circumference in relation to outcomes of infertility treatment with assisted reproductive technologies

BACKGROUND

Many studies have documented a lower likelihood of live birth with increasing body mass index among women undergoing assisted reproductive technology, but few have examined the association with waist circumference, an anthropometric measure that allows assessment of central adiposity.

OBJECTIVE

To examine the relation between baseline waist circumference and infertility treatment outcomes among women undergoing treatment with assisted reproductive technology.

MATERIALS AND METHODS

We followed up 264 women who underwent 445 assisted reproductive technology cycles for infertility treatment at the Massachusetts General Hospital between 2010 and 2017. Waist circumference was assessed at enrollment. We used cluster-weighted generalized estimating equation models to estimate the probability of live birth by tertiles of waist circumference (<77, 77-86, >86 cm), while accounting for multiple treatment cycles per woman and adjusting for age, race, smoking, infertility diagnosis, day 3 follicle-stimulating hormone, body mass index, and height.

RESULTS

Mean (standard deviation) waist circumference and body mass index were 83.6 (12.6) cm and 24.1 (4.3) kg/m², respectively. Waist circumference and body mass index were positively correlated (r = 0.69, P < .0001). Waist circumference was inversely related to the probability of live birth after adjusting for BMI and other confounders. The multivariable adjusted probability of live birth (95% confidence interval) for women in increasing tertiles of waist circumference were 53% (42-65%), 42% (32-53%), and 38% (28-50%) (P, trend = .04). When women were classified in joint categories of body mass index and waist circumference, women with a body mass index ≥25 kg/m² and a waist circumference ≥77 cm had the lowest live birth rate (38% [27-50%]), whereas women with a body mass index between 18.5 and 25 kg/m² and a waist circumference <77 cm had the highest (54% [42-66%]). The results were similar using different waist circumference cut-off values.

CONCLUSION

Waist circumference was inversely related to the probability of live birth among women undergoing assisted reproductive technology independently of body mass index.

Urinary concentrations of bisphenol A, parabens and phthalate metabolite mixtures in relation to reproductive success among women undergoing in vitro fertilization

BACKGROUND

We have previously investigated whether urinary concentrations of bisphenol A (BPA), parabens, and phthalate metabolites were individually associated with reproductive outcomes among women undergoing in vitro fertilization (IVF) treatment. However, humans are typically exposed to many man-made chemicals simultaneously. Thus, investigating one chemical at a time may not represent the effect of mixtures.

OBJECTIVE

To investigate whether urinary concentrations of BPA, parabens, and phthalate metabolite mixtures are associated with reproductive outcomes among women undergoing IVF.

METHODS

This prospective cohort study included 420 women contributing 648 IVF cycles who provided up to two urine samples per cycle prior to oocyte retrieval (N = 1145) between 2006 and 2017 at the Massachusetts General Hospital Fertility Center, and had available urine biomarker data. Urinary concentrations of BPA, parabens, and phthalate metabolites were quantified using isotope-dilution tandem mass spectrometry. Intermediate and clinical end-points of IVF treatments were abstracted from electronic medical records. Principal component analysis (PCA) and Bayesian kernel machine regression (BKMR) were used to identify main patterns of BPA, parabens, and phthalate metabolites concentrations. We used generalized linear mixed models to evaluate the association between PCA-derived factor scores, in quartiles, and IVF outcomes, using random intercepts to account for multiple IVF cycles and adjusting for known confounders. Because of temporal trends in exposure, we conducted a sensitivity analysis restricted to women who underwent IVF cycles in the earlier years of study (2006-2012).

RESULTS

Urinary concentrations of BPA, parabens, and most phthalate metabolites were significantly lower during the second half of the study period (2013-2017) than during the first half (2006-2012). None of the three factors derived from the PCA [di(2-ethylhexyl) phthalate (DEHP), non-DEHP, and paraben] was associated with IVF outcomes in the main analyses. Similarly, BKRM analyses did not identify any associations of individual urinary concentrations of BPA, paraben and phthalate metabolites with IVF outcomes while accounting for correlation between exposures. However, in sensitivity analyses restricted to women who underwent IVF cycles from 2006 to 2012, where concentrations of most phthalates and phenols were higher, there were decreases in implantation, clinical pregnancy, and live birth across quartiles of the DEHP factor. Specifically, women in the highest quartile of the DEHP factor had, on average, lower probabilities of implantation (-22% p, trend = 0.08), clinical pregnancy (-24% p, trend = 0.14), and live birth (-38% p, trend = 0.06) compared to women in the lowest quartile. Among this group of women, BKMR results did not identify any single contributor driving the decreased probabilities of live birth within the DEHP factor.

CONCLUSIONS

We confirmed that women undergoing IVF are concurrently exposed to multiple endocrine disrupting chemicals (EDCs). While we found no overall significant associations, we observed diminished pregnancy success with specific clusters of chemicals among women who underwent IVF cycles in earlier years of study, when urinary concentrations of these EDCs were higher.

Organophosphate flame-retardant metabolite concentrations and pregnancy loss among women conceiving with assisted reproductive technology

OBJECTIVE

To evaluate whether urinary concentrations of organophosphate flame retardant (PFR) metabolites are associated with pregnancy loss among women conceiving with assisted reproductive technology (ART).

DESIGN

Prospective preconception cohort of subfertile women.

SETTING

Academic hospital fertility center in Boston, Massachusetts.

PATIENT(S)

A total of 155 women conceiving 179 pregnancies with ART.

INTERVENTION(S)

None. Mean exposure to each of five PFR metabolites was estimated by averaging the specific-gravity adjusted natural log concentrations from two urine samples collected during the ART cycle of conception.

MAIN OUTCOME MEASURE(S)

Adjusted risk ratios (RRs) and 95% confidence intervals (CIs) for biochemical and total pregnancy loss (all losses <20 weeks' gestation) by quartiles of PFR metabolite concentrations were estimated using a repeated measures log-binomial model, accounting for multiple pregnancies per woman.

RESULT(S)

Of the 179 pregnancies, 31% ended in pregnancy loss (12% in biochemical loss). Among the three metabolites with high detection frequency [bis(1,3-dichloro-2-propyl) phosphate (BDCIPP), diphenyl phosphate (DPHP), and isopropylphenyl phenyl phosphate (ip-PPP)], an increased risk of biochemical loss was observed for women with DPHP concentrations in the fourth vs. first quartile (RR 1.64; 95% CI 0.61-4.39). Also found was an elevated risk of biochemical pregnancy loss among women in the highest quartile of the molar sum of urinary PFR metabolites compared with the lowest (RR 1.89; 95% CI 0.64-5.58). Urinary concentrations of ip-PPP and BDCIPP were not associated with either outcome.

CONCLUSION(S)

Among subfertile women, urinary DPHP metabolite concentrations measured during the ART cycle of conception may be associated with early pregnancy loss. Although this study is uniquely designed to investigate early markers of pregnancy success and maintenance, the small sample size likely contributed to imprecision. Given their increasing use as replacement chemicals for traditional flame retardants, exposure to PFRs may increase, and more studies will be needed to investigate their potential to impact pregnancy and reproduction.

Methodological approaches to analyzing IVF data with multiple cycles

STUDY QUESTION

Which methodological approaches are most appropriate for analyzing IVF data with multiple cycles in the context of a binary outcome?

SUMMARY ANSWER

Both mixed effect models and generalized estimating equation (GEE) modeling approaches can account for multiple IVF cycles and may reduce bias over first-cycle only approaches, but CIs were narrowest with cluster-weighted generalized estimating equation models (CWGEE).

WHAT IS KNOWN ALREADY

There is a lack of consensus among investigators regarding how to best incorporate data from multiple cycles and whether to present odds or risks in the analysis of IVF data. Failure to account for correlated outcomes within individuals and informative cluster size may lead to invalid CIs and biased estimates.

STUDY DESIGN, SIZE, DURATION

The Environment and Reproductive Health (EARTH) Study is an ongoing prospective cohort study of subfertile couples conducted at an academic medical center. This cohort was established in 2004 and follows couples seeking treatment for infertility throughout the course of their treatment and pregnancy.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Women aged 18-46 years enrolled in the EARTH Study from 2004 to 2017 who initiated at least one IVF cycle were eligible. Cycle initiation was defined as beginning ovulation induction with the intent to progress through an IVF or ICSI cycle. This analysis included 442 women undergoing 642 cycles who met the study inclusion criteria. We compared the results and interpretations of log-binomial and logistic models restricting to the first cycle, as well as mixed effects models, unweighted GEE models, and CWGEE models including all cycles. This analysis was conducted for two distinct exposures: maternal age at cycle initiation, and maternal preconception urinary concentrations of di(2-ethylhexyl) phthalate (DEHP) metabolites (previously reported to be associated with a decreased probability of live birth).

MAIN RESULTS AND THE ROLE OF CHANCE

In general, the CIs were widest for mixed effects models and narrowest for CWGEE models. Further, in models evaluating the sum of urinary concentrations of DEHP metabolites (∑DEHP, available for 91% of women), the point estimates were surprisingly different between the first-cycle and multiple-cycle models. We observed significant associations between maternal age and live birth in all models. However, we observed no associations between ∑DEHP and live birth.

LIMITATIONS, REASONS FOR CAUTION

This analysis was limited to an example dataset in which the true effect of any exposure is unknown. While this allows us to observe model performance in the context of real data, future analyses should be conducted within simulated datasets under various assumptions to further evaluate the appropriateness of each approach. In addition, we did not address differential loss to follow-up in our statistical approaches.

WIDER IMPLICATIONS OF THE FINDINGS

The use of CWGEE models should be more widely considered in the analysis of IVF data with multiple cycles per woman. The CWGEE approach is computationally simple, addresses non-ignorable (informative) cluster size, and is robust against mis-specification of the underlying covariance structure. Among the methods compared in this analysis, CWGEE models generally yielded the narrowest CIs, possibly indicating the most precise estimates. We also stress the importance of estimating risks rather than odds in the analysis of IVF data.

STUDY FUNDING/COMPETING INTEREST(S)

The project was funded by Grants (R01ES022955, R01ES009718, and P30ES000002) from the National Institutes of Health. None of the authors has any conflicts of interest to declare.