Delayed conception in women with low-urinary iodine concentrations: a population-based prospective cohort study

STUDY QUESTION

Is iodine deficiency associated with decreased fecundability?

SUMMARY ANSWER

Moderate to severe iodine deficiency is associated with a 46% decrease in fecundability.

WHAT IS KNOWN ALREADY

Iodine deficiency is common in women of childbearing age but its effect on fecundability has not been investigated.

STUDY DESIGN, SIZE, DURATION

The LIFE Study, a population-based prospective cohort study, enrolled 501 women who had discontinued contraception within 2 months to become pregnant between 2005 and 2009.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Women reported on risk factors for infertility by interview then kept daily journals of relevant information. Women used fertility monitors to time intercourse relative to ovulation then used home digital pregnancy tests to identify pregnancies on the day of expected menstruation. Urine samples for iodine analysis were collected on enrollment.

MAIN RESULTS AND THE ROLE OF CHANCE

Samples were in the deficiency range in 44.3% of participants. The group whose iodine-creatinine ratios were below 50 μg/g (moderate to severe deficiency) had a 46% reduction in fecundity (P = 0.028) compared with the group whose iodine-creatinine ratios were in the adequate range: adjusted fecundability odds ratio of becoming pregnant per cycle, 0.54 (95% confidence interval 0.31-0.94).

LIMITATIONS, REASONS FOR CAUTION

Iodine concentrations vary within individuals over time, so the data must be interpreted by group as we have done; residual confounding is possible.

WIDER IMPLICATIONS OF THE FINDINGS

Significant delays in becoming pregnant occur at iodine concentrations that are common in women in the USA and parts of Europe. Replicating these findings will be important to determine whether improving iodine status could be beneficial in improving fecundability.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the Intramural Research Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, USA. Contracts N01-HD-3-3355; N01-HD-3-3356; N01-HD-3-3358 and HHSN275201100001l/HHSN27500007. None of the authors has any conflict of interest to declare.

Male birthweight, semen quality and birth outcomes

STUDY QUESTION

What are the relations among birthweight (BW), semen parameters and birth outcomes in a population-based sample?

SUMMARY ANSWER

BW is unrelated to semen parameters, which are in turn unrelated to birth outcomes.

WHAT IS KNOWN ALREADY

In clinical settings, there has been suggestion that semen parameters are related to BW when comparing fertile and infertile men; however, findings have been less clear in more general populations.

STUDY DESIGN, SIZE, DURATION

Questionnaire data and semen samples were collected at baseline from 427 male participants of the population-based Longitudinal Investigation of Fertility and the Environment (LIFE) prospective cohort study from 2005 to 2009, who were followed prospectively to assess pregnancy outcomes among 226 singleton births.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Men of at least 18 years of age who were married or in a committed relationship and trying to conceive were eligible for participation; physician-diagnosed infertility was an exclusion criterion. Participants were recruited from two geographic areas and semen samples were analyzed for 34 quality parameters categorized as general, motility, morphology, sperm head and sperm chromatin structure using methods including computer-aided semen analysis integrated visual optical system and sperm chromatin structure assay. Linear and mixed models were used for statistical analysis of the relations between men's BW, semen parameters, and BW, gestational age at delivery, birth length, head circumference and ponderal index of singleton births.

MAIN RESULTS AND THE ROLE OF CHANCE

No association was observed between male BW and semen parameters or birth outcomes. Few associations were observed between semen parameters and birth outcomes, and the observed statistically significant associations were isolated and without a consistent pattern that would suggest an association between BW and birth outcomes.

LIMITATIONS, REASONS FOR CAUTION

Men's BW was self-reported and may be subject to some imprecision. Semen analysis was performed the day after collection, an approach that impacts the assessment of motility and that may limit inference from our analyses of motility measures. In addition, inclusion criteria for selection into the cohort limits generalizability to generally healthy couples trying to conceive and without known subfertility.

WIDER IMPLICATIONS OF THE FINDINGS

Despite suggestions from prior studies of male in utero exposures impacting BW and male reproductive health, there appears to be little support for such relations in this generally healthy population.

STUDY FUNDING/COMPETING INTEREST(S)

Supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (N01-HD-3-3355, N01-HD-3-3356 and NOH-HD-3-3358). The authors report no competing interests, and a Memo of Understanding with the National Institute of Occupational Safety and Health (NIOSH) for semen analysis.

TRIAL REGISTRATION NUMBER

Not applicable.

A data-driven search for semen-related phenotypes in conception delay

Sperm count, morphology, and motility have been reported to be predictive of pregnancy, although with equivocal basis prompting some authors to question the prognostic value of semen analysis. To assess the utility of including semen quality data in predicting conception delay or requiring >6 cycles to become pregnant (referred to as conception delay), we utilized novel data-driven analytic techniques in a pre-conception cohort of couples prospectively followed up for time-to-pregnancy. The study cohort comprised 402 (80%) male partners who provided semen samples and had time-to-pregnancy information. Female partners used home pregnancy tests and recorded results in daily journals. Odds ratios (OR), false discovery rates, and 95% confidence intervals (CIs) for conception delay (time-to-pregnancy > 6 cycles) were estimated for 40 semen quality phenotypes comprising 35 semen quality endpoints and 5 closely related fecundity determinants (body mass index, time of contraception, lipids, cotinine and seminal white blood cells). Both traditional and strict sperm phenotype measures were associated with lower odds of conception delay. Specifically, for an increase in percent morphologically normal spermatozoa using traditional methods, we observed a 40% decrease in conception delay (OR = 0.6, 95% CI = 0.50, 0.81; p = 0.0003). Similarly, for an increase in strict criteria, we observed a 30% decrease in odds for conception delay (OR = 0.7, 95% CI = 0.52, 0.83; p = 0.001). On the other hand, an increase in percent coiled tail spermatozoa was associated with a 40% increase in the odds for conception delay (OR = 1.4, 95% CI = 1.12, 1.75; p = 0.003). However, our findings suggest that semen phenotypes have little predictive value of conception delay (area under the curve of 73%). In a multivariate model containing significant semen factors and traditional risk factors (i.e. age, body mass index, cotinine and ever having fathered a pregnancy), there was a modest improvement in prediction of conception delay (16% increase in area under the curve, p < 0.0002).

Infertility treatment and children's longitudinal growth between birth and 3 years of age

STUDY QUESTION

Does early childhood growth from birth through to 3 years of age differ by mode of conception?

SUMMARY ANSWER

Findings suggest early childhood growth was comparable for children irrespective of infertility treatment, but twins conceived with ovulation induction with or without intrauterine insemination (OI/IUI) were slightly smaller than twins conceived without treatment.

WHAT IS KNOWN ALREADY

Although studies have found that babies conceived with infertility treatment are born lighter and earlier than infants conceived without treatment, little research especially for non-assisted reproductive technology (ART) treatments has focused on their continued growth during early childhood.

STUDY DESIGN, SIZE, DURATION

Upstate KIDS recruited infants born (2008-2010) to resident upstate New York mothers. Infants were sampled based on birth certificate indication of infertility treatment; specifically, for every singleton conceived by infertility treatment, three singletons without infertility treatment were recruited and matched on region of birth. All multiple births irrespective of treatment were also recruited. Children were prospectively followed, returning questionnaires every 4-6 months until 3 years of age. In total, 3905 singletons, 1129 sets of multiples (96% of whom were twins) enrolled into the study. Analyses included 3440 (88%) singletons (969 conceived with treatment; specifically, 433 with ART and 535 with OI/IUI) and 991 (88%) sets of multiples (439 conceived with treatment; specifically 233 with ART and 206 with OI/IUI) with growth data available.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Mothers reported infertility treatment use at baseline and children's height and weight from pediatric visits. Self-reported use of ART was previously verified by linkage with the US Society for Assisted Reproductive Technology Clinic Outcome Reporting System (SART CORS) database. Mixed linear models with cubic splines accounting for age and age-gender interactions were used to estimate mean differences in growth from birth to 3 years by infertility treatment status and adjusting for maternal age, race, education, private insurance, smoking status during pregnancy, maternal pre-pregnancy and paternal body mass indices (BMI).

MAIN RESULTS AND THE ROLE OF CHANCE

Compared with singletons conceived without treatment (n = 2471), singletons conceived by infertility treatment (433 by assisted reproductive technologies (ART), 535 by OI/IUI and 1 unknown specific type) did not differ in growth. Compared with twins not conceived with treatment (n = 1076), twins conceived with OI/IUI (n = 368) weighed slightly less over follow-up (122 g). They were also proportionally smaller for their length (-0.17 weight-for-length z-score units). No differences in mean size over the 3 years were observed for twins conceived by ART, though some evidence of rapid weight gain from birth to 4 months (adjusted OR 1.08; 95% CI: 1.00-1.16) suggestive of catch up growth was observed.

LIMITATIONS, REASONS FOR CAUTION

Participants from upstate New York may not be representative of US infants. Although accounted for in statistical analysis, attrition during follow-up may have limited power to detect small differences.

WIDER IMPLICATIONS OF THE FINDINGS

This study is the first to prospectively track the growth of children conceived with and without infertility treatment in the USA, including a substantial number of twins. Our findings are similar to what was previously observed in the ART literature outside of the states.

STUDY FUNDING/COMPETING INTERESTS

Supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD; contracts #HHSN275201200005C, #HHSN267200700019C). Authors have no competing interests to declare.

TRIAL REGISTRATION NUMBER

Not applicable.

Paternal exposures to environmental chemicals and time-to-pregnancy: overview of results from the LIFE study

Published findings from the Longitudinal Investigation of Fertility and the Environment (LIFE) Study regarding the relation between environmental chemicals and couple fecundity, as measured by time-to-pregnancy (TTP), are reviewed with a particular focus on role of the male partner. The LIFE Study recruited 501 couples from 16 counties in two U.S. states upon discontinuing contraception for purposes of becoming pregnant. Upon enrollment, couples provided a blood and urine sample for the quantification of persistent and non-persistent environmental chemicals, respectively, and then completed daily journals until pregnant or up to one year of trying. Female partners used fertility monitors to aid the timing of intercourse relative to ovulation, and digital home pregnancy test kits on the day of expected menses. Chemical classes included: metals, persistent organic pollutants, environmental phenols, and phthalates that were quantified using inductively coupled plasma mass spectrometry or isotope dilution high-resolution or tandem mass spectrometry. Time-to-pregnancy (TTP) was defined as the number of prospectively observed menstrual cycles required for pregnancy. Fecundability odds ratios (FORs) and 95% confidence intervals (CIs) were estimated for each chemical and partner after adjusting for potential confounders and accounting for right censoring and time off contraception. FORs < 1 are suggestive of diminished fecundity or a longer TTP. Significant reductions (ranging from 17-31%) in couple fecundity were observed for male partners' concentration of lead (0.83; 0.70, 0.98), 2,2',4,4'-tetrahydroxybenzophenone (0.69; 0.49, 0.97), monobenzyl (0.80; 0.67, 0.97), and monomethyl (0.81; 0.70, 0.94) phthalates after adjusting for the female partners' concentrations. Seven PCB congeners quantified in men's serum were associated with a 17-29% reduction in couple fecundity. Our findings underscore the importance of a couple-based exposure design, inclusive of the male partner, when assessing couple-dependent outcomes such as TTP to avoid misinterpretation of results based only upon the female partner.

Choice of underwear and male fecundity in a preconception cohort of couples

Our objective was to investigate the relationship between male underwear-type worn during daytime/bedtime and male fecundity as measured by semen quality and time-to-pregnancy. We used data from a prospective preconception cohort conducted in 16 counties in Michigan and Texas, USA. 501 couples were enrolled and followed for 12 months of trying, which facilitated capture of time-to-pregnancy (in cycles), 6-cycle conception delay, and 12-month infertility. Male partners provided semen samples via in-home collection for next-day semen analysis comprised of 35 semen quality endpoints. At enrollment, men provided information on type of underwear worn during daytime and bedtime and were classified into 6 categories by underwear choice (n = 491): (i) briefs day/night, (ii) boxer-briefs day/night, (iii) boxers day/night, (iv) briefs day and boxers/none at night, (v) boxer-briefs day and boxers/none at night, (vi) boxers day and none at night. 473 (96%) men had semen analysis performed. Men switching from their usual daytime underwear to boxers/none for bed (groups 4, 5, 6) had the most evidence of change in semen quality endpoints (10 of 11 differences) relative to men wearing briefs day/night (group 1). Group 4 men had lower percent of sperm with coiled tail (β = -0.18, 95% CI: -0.35, -0.01), higher percent round (β = 0.22, 95% CI: 0.01, 0.42), number of immature sperm (β = 0.44, 95% CI: 0.11, 0.77), and amplitude head displacement (β = 0.57, 95% CI: 0.10, 1.03). Group 5 men had higher sperm head perimeter (β=0.17, 95% CI: 0.002, 0.34), amplitude head displacement (β = 0.47, 95% CI: 0.03, 0.91), percent cytoplasmic droplet (β = 0.44, 95% CI: 0.11, 0.77) and high DNA stainability (β=0.39, 95% CI: 0.01, 0.78). After false discovery rate control, no differences remained significant. No significant differences in time-to-pregnancy, conception delay, or infertility were observed. In summary, male underwear choice is associated with few differences in semen parameters; no association with time-to-pregnancy is observed providing reassurance to couples attempting pregnancy.

Signs and symptoms associated with early pregnancy loss: findings from a population-based preconception cohort

STUDY QUESTION

What is the relationship between signs and symptoms of early pregnancy and pregnancy loss <20 weeks' gestation?

SUMMARY ANSWER

Vaginal bleeding is associated with increased incidence of early pregnancy loss, with more severe bleeding and bleeding accompanied by lower abdominal cramping associated with greater incidence of loss; conversely, vomiting is associated with decreased incidence of early pregnancy loss, even in the setting of vaginal bleeding, while nausea alone is not.

WHAT IS KNOWN ALREADY

Two previous cohort studies with preconception enrollment suggested that bleeding is associated with loss while nausea is inversely associated with loss though these studies were limited by small study size and reporting after loss ascertainment. No prior preconception cohort study has examined multiple signs and symptoms in relation to pregnancy loss.

STUDY DESIGN, SIZE, DURATION

Population-based preconception cohort of 501 couples discontinuing contraception to try for pregnancy in 16 counties in Michigan and Texas, USA. Participants were followed daily until positive home pregnancy test or 12 months of trying without an hCG pregnancy; women who became pregnant were followed daily from 2 to 7 weeks post-conception.

PARTICIPANTS, SETTING, METHODS

Three hundred and forty-seven women had a positive home pregnancy test denoting hCG pregnancy. Three hundred and forty-one women remained after excluding ineligible pregnancies. Women recorded daily from 2 to 7 weeks post-conception their signs and symptoms, including vaginal bleeding (none, spotting, light, moderate and heavy), lower abdominal cramping, nausea and vomiting. Pregnancy losses were ascertained by a subsequent negative home pregnancy test, clinical confirmation or onset of menses, depending on gestational age at loss; time-to-loss was measured in days post-conception. Cumulative incidence functions and 95% confidence intervals (CIs) were constructed for each sign or symptom, and hazard ratios (HRs) and 95% CIs for presence compared with absence of signs or symptoms were estimated using Cox proportional hazard models.

MAIN RESULTS AND THE ROLE OF CHANCE

Women experienced lower abdominal cramping (85%), nausea (48%), vomiting (46%) and light/moderate/heavy vaginal bleeding (24%) during early pregnancy. Ninety-five (28%) women experienced a loss. Cumulative incidence of pregnancy loss varied by symptomatology: 19% for vomiting, 27% for lower abdominal cramping, 35% for nausea only, 52% for vaginal bleeding, 81% for vaginal bleeding with lower abdominal cramping. Incidence of pregnancy loss was increased among women with vaginal bleeding (HR: 3.62, 95% CI: 2.29-5.74) and among women with vaginal bleeding and lower abdominal cramping (HR: 5.03, 95% CI: 2.07-12.20). Incidence of pregnancy loss was decreased for women with vomiting (HR: 0.51, 95% CI: 0.30-0.86). In the setting of vaginal bleeding with lower abdominal cramping, vomiting reduced the incidence of pregnancy loss (HR: 0.24, 95% CI: 0.11-0.56).

LIMITATIONS, REASONS FOR CAUTION

There were few losses beyond 14 weeks gestation; thus, the precision of our findings related to losses occurring after the first trimester is limited.

WIDER IMPLICATIONS OF THE FINDINGS

By using sensitive home pregnancy tests, we are able to document and characterize the cumulative incidence of the earliest pregnancy losses, which constitute the majority of losses. The use of daily, prospective capture of signs and symptoms relative to ascertainment of pregnancy loss minimizes potential biases associated with reporting after rather than before a loss, which could potentially distort the relationship between signs and symptoms and pregnancy loss. The findings of our study suggest that it may be useful to develop prognostic models for pregnancy loss based on signs and symptoms.

STUDY FUNDING/COMPETING INTERESTS

This study was supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health (contract numbers N01-HD-3-3355; N01-HD-3-3356; N01-HD-3-3358). The authors have no conflict of interest to declare.

Associations between urinary phthalate concentrations and semen quality parameters in a general population

STUDY QUESTION

Are urinary phthalate concentrations associated with altered semen quality parameters among males recruited from the general population?

SUMMARY ANSWER

Urinary levels of metabolites of phthalate diesters are associated with lower total sperm counts, larger sperm head sizes, and higher percentages of morphologically abnormal sperm.

WHAT IS KNOWN ALREADY

High dose experiments in rats implicate phthalates as anti-androgens. Studies involving infertile men seeking care suggest that phthalates influence measures of semen quality raising concern about the implications for men in the general population.

STUDY DESIGN, SIZE, DURATION

This prospective cohort study comprised 501 male partners in couples discontinuing contraception to become pregnant, who were recruited from 16 US counties using population-based sampling frameworks from 2005 to 2009.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Urine and semen samples were obtained at baseline from 473 (94%) men, of whom 378 (80%) men provided a second sample the following month. Urine was analyzed for 14 monoester metabolites of phthalate diesters by high-performance liquid chromatography coupled to tandem mass spectrometry. Semen samples were analyzed for 34 quality parameters categorized as general, motility, morphology, sperm head and sperm chromatin structure.

MAIN RESULTS AND THE ROLE OF CHANCE

Urinary mono-[2-(carboxymethyl) hexyl] phthalate (MCMHP), mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono-benzyl phthalate (MBzP), and mono-isononyl phthalate (MNP) were significantly associated with lower total sperm counts and concentrations, larger sperm head sizes, higher proportions of megalo head sperm morphology, and/or other morphological changes. Urinary mono-methyl phthalate (MMP) and mono-cyclohexyl phthalate (MCPP) were significantly associated with lower sperm motility, and urine mono-2-ethylhexyl phthalate (MEHP) was significantly associated with higher sperm motility.

LIMITATIONS, REASONS FOR CAUTION

While adverse associations were observed, the implications of the findings for couple fecundity and fertility remain to be established. Cautious interpretation is needed in light of reliance on a single measurement of phthalate measure and no correction for multiple comparisons.

Endometriosis diagnosis and staging by operating surgeon and expert review using multiple diagnostic tools: an inter-rater agreement study

OBJECTIVE

To determine agreement on endometriosis diagnosis between real-time laparoscopy and subsequent expert review of digital images, operative reports, magnetic resonance imaging (MRI), and histopathology, viewed sequentially.

DESIGN

Inter-rater agreement study.

SETTING

Five urban surgical centres.

POPULATION

Women, aged 18-44 years, who underwent a laparoscopy regardless of clinical indication. A random sample of 105 women with and 43 women without a postoperative endometriosis diagnosis was obtained from the ENDO study.

METHODS

Laparoscopies were diagnosed, digitally recorded, and reassessed.

MAIN OUTCOME MEASURES

Inter-observer agreement of endometriosis diagnosis and staging according to the revised American Society for Reproductive Medicine criteria. Prevalence and bias-adjusted kappa values (κ) were calculated for diagnosis, and weighted κ values were calculated for staging.

RESULTS

Surgeons and expert reviewers had substantial agreement on diagnosis and staging after viewing digital images (n = 148; mean κ = 0.67, range 0.61-0.69; mean κ = 0.64, range 0.53-0.78, respectively) and after additionally viewing operative reports (n = 148; mean κ = 0.88, range 0.85-0.89; mean κ = 0.85, range 0.84-0.86, respectively). Although additionally viewing MRI findings (n = 36) did not greatly impact agreement, agreement substantially decreased after viewing histological findings (n = 67), with expert reviewers changing their assessment from a positive to a negative diagnosis in up to 20% of cases.

CONCLUSION

Although these findings suggest that misclassification bias in the diagnosis or staging of endometriosis via visualised disease is minimal, they should alert gynaecologists who review operative images in order to make decisions on endometriosis treatment that operative reports/drawings and histopathology, but not necessarily MRI, will improve their ability to make sound judgments.

TWEETABLE ABSTRACT

Endometriosis diagnosis and staging agreement between expert reviewers and operating surgeons was substantial.

Pain typology and incident endometriosis

STUDY QUESTION

What are the pain characteristics among women, with no prior endometriosis diagnosis, undergoing laparoscopy or laparotomy regardless of clinical indication?

SUMMARY ANSWER

Women with surgically visualized endometriosis reported the highest chronic/cyclic pain and significantly greater dyspareunia, dysmenorrhea, and dyschezia compared with women with other gynecologic pathology (including uterine fibroids, pelvic adhesions, benign ovarian cysts, neoplasms and congenital Müllerian anomalies) or a normal pelvis.

WHAT IS KNOWN ALREADY

Prior research has shown that various treatments for pain associated with endometriosis can be effective, making identification of specific pain characteristics in relation to endometriosis necessary for informing disease diagnosis and management.

STUDY DESIGN, SIZE, DURATION

The study population for these analyses includes the ENDO Study (2007-2009) operative cohort: 473 women, ages 18-44 years, who underwent a diagnostic and/or therapeutic laparoscopy or laparotomy at one of 14 surgical centers located in Salt Lake City, UT or San Francisco, CA. Women with a history of surgically confirmed endometriosis were excluded.

PARTICIPANTS/MATERIALS, SETTING AND METHODS

Endometriosis was defined as surgically visualized disease; staging was based on revised American Society for Reproductive Medicine (rASRM) criteria. All women completed a computer-assisted personal interview at baseline specifying 17 types of pain (rating severity via 11-point visual analog scale) and identifying any of 35 perineal and 60 full-body front and 60 full-body back sites for which they experienced pain in the last 6 months.

MAIN RESULTS AND THE ROLE OF CHANCE

There was a high prevalence (≥30%) of chronic and cyclic pelvic pain reported by the entire study cohort regardless of post-operative diagnosis. However, women with a post-operative endometriosis diagnosis, compared with women diagnosed with other gynecologic disorders or a normal pelvis, reported more cyclic pelvic pain (49.5% versus 31.0% and 33.1%, P < 0.001). Additionally, women with endometriosis compared with women with a normal pelvis experienced more chronic pain (44.2 versus 30.2%, P = 0.04). Deep pain with intercourse, cramping with periods, and pain with bowel elimination were much more likely reported in women with versus without endometriosis (all P < 0.002). A higher percentage of women diagnosed with endometriosis compared with women with a normal pelvis reported vaginal (22.6 versus 10.3%, P < 0.01), right labial (18.4 versus 8.1%, P < 0.05) and left labial pain (15.3 versus 3.7%, P < 0.01) along with pain in the right/left hypogastric and umbilical abdominopelvic regions (P < 0.05 for all). Among women with endometriosis, no clear and consistent patterns emerged regarding pain characteristics and endometriosis staging or anatomic location.

LIMITATIONS, REASONS FOR CAUTION

Interpretation of our findings requires caution given that we were limited in our assessment of pain characteristics by endometriosis staging and anatomic location due to the majority of women having minimal (stage I) disease (56%) and lesions in peritoneum-only location (51%). Significance tests for pain topology related to gynecologic pathology were not corrected for multiple comparisons.

WIDER IMPLICATIONS OF THE FINDINGS

Results of our research suggest that while women with endometriosis appear to have higher pelvic pain, particularly dyspareunia, dysmenorrhea, dyschezia and pain in the vaginal and abdominopelvic area than women with other gynecologic disorders or a normal pelvis, pelvic pain is commonly reported among women undergoing laparoscopy, even among women with no identified gynecologic pathology. Future research should explore causes of pelvic pain among women who seek out gynecologic care but with no apparent gynecologic pathology. Given our and other's research showing little correlation between pelvic pain and rASRM staging among women with endometriosis, further development and use of a classification system that can better predict outcomes for endometriosis patients with pelvic pain for both surgical and nonsurgical treatment is needed.

STUDY FUNDING/COMPETING INTERESTS

Supported by the Intramural Research Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development (contracts NO1-DK-6-3428, NO1-DK-6-3427, and 10001406-02). The authors have no potential competing interests.

Bisphenol A, benzophenone-type ultraviolet filters, and phthalates in relation to uterine leiomyoma

Bisphenol A, benzophenone-type UV filters, and phthalates are chemicals in high production and use including in a range of personal care products. Exposure of humans to these chemicals has been shown to affect endocrine function. Although short-lived, widespread exposure may lead to continual opportunity for these chemicals to elicit health effects in humans. The association of these chemicals with incident uterine leiomyoma, an estrogen sensitive disease, is not known. Urinary concentrations of bisphenol A (BPA), five benzophenone-type UV filters (2-hydroxy-4-methoxybenzophenone (2OH-4MeO-BP), 2,4-dihydroxybenzophenone (2,4OH-BP), 2,2׳-dihydroxybenzophenone (2,2׳OH-4MeO-BP), 2,2׳4,4׳-tetrahydroxybenzophenone (2,2׳4,4׳OH-BP), and 4-hydroxybenzophenone (4OH-BP), and 14 phthalate monoesters were quantified in 495 women who later underwent laparoscopy/laparotomy at 14 clinical sites for the diagnosis of fibroids. Significantly higher geometric mean creatinine-corrected concentrations of BPA, 2,4OH-BP, and 2OH-4MeO-BP were observed in women with than without fibroids [BPA: 2.09µg/g vs. 1.46µg/g p=0.004; 2,4OH-BP:11.10µg/g vs. 6.71µg/g p=0.01; 2OH-4MeO-BP: 11.31µg/g vs. 6.10µg/g p=0.01]. Mono-methyl phthalate levels were significantly lower in women with than without fibroids (1.78µg/g vs. 2.40µg/g). However, none of the exposures were associated with a significant odds ratio even when adjusting for relevant covariates. There was a lack of an association between select nonpersistent chemicals and the odds of a fibroid diagnosis.

Successive time to pregnancy among women experiencing pregnancy loss

STUDY QUESTION

Is time to pregnancy (TTP) similar across successive pregnancy attempts among women experiencing pregnancy loss?

SUMMARY ANSWER

TTP after a loss may be longer compared with TTP before a loss.

WHAT IS KNOWN ALREADY

Two pregnancy cohort studies have reported that TTP is similar across pregnancy attempts in fertile women. However, this has not been investigated among women experiencing pregnancy losses.

STUDY DESIGN, SIZE, DURATION

Data for this analysis come from the Longitudinal Investigation of Fertility and the Environment Study, a population-based, preconception cohort of couples attempting pregnancy. During 2005-2009, recruitment was targeted to 16 counties in Michigan and Texas with reported exposures to persistent environmental chemicals. A total of 501 couples were recruited and followed for up to 12 months of pregnancy attempts allowing for continued participation of women with pregnancy losses until censoring.

PARTICIPANTS, SETTING, METHODS

We assessed TTP among 70 couples recruited upon discontinuing contraception for purposes of becoming pregnant and experiencing ≥1 prospectively observed pregnancy losses during 12 months of trying. There were 61 couples who contributed two pregnancy attempts and 9 who contributed three. Women were instructed in the use of urine-based home fertility monitors to time intercourse relative to ovulation and recorded their bleeding patterns in daily journals. TTP was defined as the number of menstrual cycles taken to achieve pregnancy. Women were also instructed in the use of home digital pregnancy tests and asked to begin pregnancy testing on the day of expected menses. Women recorded the results of their pregnancy tests in a daily journal with a single positive pregnancy test result indicating an hCG-confirmed pregnancy. Pregnancy losses were ascertained from a subsequent recorded negative pregnancy test or clinically confirmed loss. We estimated fecundability odds ratios (FORs) comparing subsequent to first TTP using discrete Cox models with robust standard errors, accounting for cycles off contraception before study entry and adjusting for maternal age, body mass index, reproductive history and time-varying cigarette, alcohol and caffeine usage while trying.

MAIN RESULTS AND THE ROLE OF CHANCE

The mean female age was 30.3 ± 4.3 years; 21% had a prior pregnancy loss before study entry. Of the second and third attempts, 59 and 43%, respectively, were longer compared with the first attempt. FORs <1 suggest reduced fecundability or a longer TTP when comparing the second with the first attempt (0.42, 95% confidence interval (CI): 0.28, 0.65), and similarly for the third relative to the first attempt (0.64, 95% CI: 0.18, 2.36). TTP in the second attempt was a median of 1 cycle longer (interquartile range: 0, 3 cycles) compared with TTP in the first attempt.

LIMITATIONS, REASONS FOR CAUTION

As this is the first study to investigate successive TTP exclusively among women experiencing pregnancy loss, our findings await corroboration since most losses occurred early in gestation. As such, the generalizability of our findings for all pregnancy losses awaits further research. We also had limited power to detect a reduction in fecundability for the third compared with first pregnancy attempt.

WIDER IMPLICATIONS OF THE FINDINGS

Unlike fertile women, TTP in women experiencing early pregnancy losses may trend towards longer subsequent attempts. If the findings are corroborated, women experiencing losses may benefit from counselling regarding trying times.

STUDY FUNDING/COMPETING INTERESTS

This research was supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (contracts N01-HD-3-3355, N01-HD-3-3356 and NOH-HD-3-3358). K.J.S. was supported by an Intramural Research Training Award from the Eunice Kennedy Shriver National Institute of Child Health and Human Development, Division of Intramural Population Health Research. The authors have no conflicts of interest to declare.

Preconception stress increases the risk of infertility: results from a couple-based prospective cohort study--the LIFE study

STUDY QUESTION

Are women's stress levels prospectively associated with fecundity and infertility?

SUMMARY ANSWER

Higher levels of stress as measured by salivary alpha-amylase are associated with a longer time-to-pregnancy (TTP) and an increased risk of infertility.

WHAT IS KNOWN ALREADY

Data suggest that stress and reproduction are interrelated; however, the directionality of that association is unclear.

STUDY DESIGN, SIZE, DURATION

In 2005-2009, we enrolled 501 couples in a prospective cohort study with preconception enrollment at two research sites (Michigan and Texas, USA). Couples were followed for up to 12 months as they tried to conceive and through pregnancy if it occurred. A total of 401 (80%) couples completed the study protocol and 373 (93%) had complete data available for this analysis.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Enrolled women collected saliva the morning following enrollment and then the morning following their first observed study menses for the measurement of cortisol and alpha-amylase, which are biomarkers of stress. TTP was measured in cycles. Covariate data were captured on both a baseline questionnaire and daily journals.

MAIN RESULTS AND THE ROLE OF CHANCE

Among the 401 (80%) women who completed the protocol, 347 (87%) became pregnant and 54 (13%) did not. After adjustment for female age, race, income, and use of alcohol, caffeine and cigarettes while trying to conceive, women in the highest tertile of alpha-amylase exhibited a 29% reduction in fecundity (longer TTP) compared with women in the lowest tertile [fecundability odds ratios (FORs) = 0.71; 95% confidence interval (CI) = (0.51, 1.00); P < 0.05]. This reduction in fecundity translated into a >2-fold increased risk of infertility among these women [relative risk (RR) = 2.07; 95% CI = (1.04, 4.11)]. In contrast, we found no association between salivary cortisol and fecundability.

LIMITATIONS, REASONS FOR CAUTION

Due to fiscal and logistical concerns, we were unable to collect repeated saliva samples and perceived stress questionnaire data throughout the duration of follow-up. Therefore, we were unable to examine whether stress levels increased as women continued to fail to get pregnant. Our ability to control for potential confounders using time-varying data from the daily journals, however, minimizes residual confounding.

WIDER IMPLICATIONS OF THE FINDINGS

This is the first US study to demonstrate a prospective association between salivary stress biomarkers and TTP, and the first in the world to observe an association with infertility.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (contracts #N01-HD-3-3355, N01-HD-3-3356, N01-HD-3358). There are no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

Not applicable.

Lipid concentrations and semen quality: the LIFE study

The decline in sperm count rates over the last 50 years appears to parallel the rising prevalence of obesity. As lipid levels are strongly associated with obesity, high lipids levels or hyperlipidaemia may thus play an important role in the decline in fertility in addition to other environmental or lifestyle factors. The objective of this population based cohort study was to evaluate the association between men's serum lipid concentrations and semen quality parameters among 501 male partners of couples desiring pregnancy and discontinuing contraception. Each participant provided prospectively up to two semen samples (94% of men provided one or more semen samples, and 77% of men provided a second sample approximately 1 month later). Linear mixed effects models were used to estimate the associations between baseline lipid concentrations and semen quality parameters, adjusted for age, body mass index and race. We found that higher levels of serum total cholesterol, free cholesterol and phospholipids were associated with a significantly lower percentage of spermatozoa with intact acrosome and smaller sperm head area and perimeter. Our results suggest that lipid concentrations may affect semen parameters, specifically sperm head morphology, highlighting the importance of cholesterol and lipid homeostasis for male fecundity.

A two-part model for reference curve estimation subject to a limit of detection

Reference curves are commonly used to identify individuals with extreme values of clinically relevant variables or stages of progression which depend naturally on age or maturation. Estimation of reference curves can be complicated by a technical limit of detection (LOD) that censors the measurement from the left, as is the case in our study of reproductive hormone levels in boys around the time of the onset of puberty. We discuss issues with common approaches to the LOD problem in the context of our pubertal hormone study, and propose a two-part model that addresses these issues. One part of the proposed model specifies the probability of a measurement exceeding the LOD as a function of age. The other part of the model specifies the conditional distribution of a measurement given that it exceeds the LOD, again as a function of age. Information from the two parts can be combined to estimate the identifiable portion (i.e. above the LOD) of a reference curve and to calculate the relative standing of a given measurement above the LOD. Unlike some common approaches to LOD problems, the two-part model is free of untestable assumptions involving unobservable quantities, flexible for modeling the observable data, and easy to implement with existing software. The method is illustrated with hormone data from the Third National Health and Nutrition Examination Survey.

Polychlorinated biphenyl serum concentrations, lifestyle and time-to-pregnancy

BACKGROUND

Consumption of fish contaminated with polychlorinated biphenyls (PCBs) and prenatal PCB serum concentrations have been associated with a longer time-to-pregnancy (TTP). However, the relationship between preconception serum PCBs concentrations and TTP has not been previously studied.

METHODS

Eighty-three women (contributing 442 menstrual cycles) planning pregnancies completed daily diaries regarding menstruation, intercourse, home pregnancy test results, and reported use of alcohol and cigarettes. TTP denoted the number of observed menstrual cycles required for pregnancy. Preconception blood specimens underwent toxicologic analysis for 76 PCB congeners via gas chromatography with electron capture; serum lipids were quantified with enzymatic methods. A priori, PCB congeners were summed into a total and three groupings-estrogenic, anti-estrogenic and other-and entered into discrete analogs of Cox models with time-varying covariates to estimate fecundability odds ratios (FOR) and corresponding 95% confidence intervals (CIs).

RESULTS

Estrogenic and anti-estrogenic PCB concentrations (ng/g serum) conferred reduced FORs in fully adjusted models (0.32; 95% CI 0.03, 3.90 and 0.01: 95% CI < 0.00, 1.99, respectively). Reduced FORs (0.96) were observed for alcohol consumption standardized to a 28-day menstrual cycle in the same adjusted model (FOR = 0.96; 95% CI 0.93, 1.00).

CONCLUSIONS

These data suggest that environmental exposures including those amenable to change, such as alcohol consumption, may impact female fecundity. The findings are sensitive to model specification and PCB groupings, underscoring the need to further assess the impact of chemical mixtures on sensitive reproductive outcomes, such as TTP, especially in the context of lifestyle factors which are amenable to change, thereby improving reproductive health.

Müllerianosis

Müllerianosis may be defined as an organoid structure of embryonic origin; a choristoma composed of müllerian rests--normal endometrium, normal endosalpinx, and normal endocervix--singly or in combination, incorporated within other normal organs during organogenesis. A choristoma is a mass of histologically normal tissue that is "not normally found in the organ or structure in which it is located" (Choristoma, 2006). Müllerian choristomas are a subset of non-müllerian choristomas found throughout the body. Histologically, endometrial-müllerianosis and endometriosis are both composed of endometrial glands and stroma, but there the similarity ends. Their pathogenesis is different. Sampson faced the same difficulty with pathogenesis and nomenclature when he wrote: "The nomenclature of misplaced endometrial or müllerian lesions is a difficult one to decide upon." "The term müllerian would be inclusive and correct, but unfortunately it suggests an embryonic origin." Sampson then divided "misplaced endometrial or müllerian tissue" into "four or possibly five groups, according to the manner in which this tissue reached its ectopic location" (Sampson, 1925). Sampson's classification of heterotopic or misplaced endometrial tissue is based on pathogenesis: 1) "direct or primary endometriosis" [adenomyosis]; "a similar condition occurs in the wall of the tube from its invasion by the tubal mucosa" [endosalpingiosis]; 2) "peritoneal or implantation endometriosis;" 3) "transplantation endometriosis;" 4) "metastatic endometriosis;" and 5) "developmentally misplaced endometrial tissue. (I admit the possibility of such a condition, but have never been able to appreciate it.)" (Sampson, 1925). It is precisely this condition "developmentally misplaced endometrial tissue," [müllerianosis] that is the subject of this review.

Time to pregnancy and multiple births

BACKGROUND

Mothers of multiples are alleged to be more fecund than mothers of singletons. Some authors have suggested monitoring twinning rates for assessing temporal changes in a population's reproductive health.

METHODS

Using a nested case-control design, we estimated the odds of a multiple birth in relation to fecundity in the US Collaborative Perinatal Project inclusive of 8546 pregnant women who reported a known time-to-pregnancy (TTP) upon enrolment in the cohort, 1959-1966. Case mothers comprised 81 women giving birth to twins/triplets; control mothers comprised 243 women giving birth to singletons matched to case mothers on maternal age at a ratio of 3:1. The odds ratio (OR) for a multiple birth within 6 months of trying adjusting for maternal age and prior pregnancies was estimated using logistic regression. Discrete time Cox regression analysis was also utilized to estimate the fecundability OR.

RESULTS

Women with a TTP of <or=6 months were more likely to have a multiple birth than women reporting a TTP of >6 months [OR=1.95; 95% confidence interval (95% CI)=1.09-3.51]. Excluding pregnancies after 13+ months resulted in a loss of precision (OR=2.14; 95% CI=0.90-5.04).

CONCLUSIONS

These data support higher fecundity among mothers of multiples than mothers of singletons.

Research hurdles complicating the analysis of infertility treatment and child health

Research aimed at the empirical evaluation of infertility treatment including assisted reproductive technologies (ART) on child health and development is hampered by investigators' inability to methodologically separate possible treatment effects from underlying fecundity impairments. While the literature continues to identify ART as a risk factor for many child health outcomes, less attention has been paid to the methodologic rigor needed to answer this question. We identify aspects of fecundity and the nuances of medical practice that need to be considered and captured when designing epidemiologic investigations aimed at assessing ART and child health. These include: (i) the use of prospective study designs in which the unit of analysis (cycle versus individual versus couple) is defined; (ii) data collection on relevant time-varying covariates at, before and during treatment; and (iii) the use of statistical techniques appropriate for hierarchical data and correlated exposures. While none of these issues in and by itself is unique to ART research, attention to these issues has been lacking in much of the published research limiting our ability to evaluate health consequences for children. Longitudinal studies of children conceived with ART will benefit from attention to these issues and, hopefully, produce answers to lingering questions about safety.

Environmental PCB exposure and risk of endometriosis

BACKGROUND

Hormonally active environmental agents have recently been associated with the development of endometriosis.

METHODS

We undertook a study to assess the relationship between endometriosis, an estrogen-dependent gynaecological disease, and 62 individual polychlorinated biphenyl (PCBs) congeners. We enrolled 84 eligible women aged 18-40 years undergoing laparoscopy for study, which included an interview and blood specimen (n=79; 94%). Thirty-two women had visually confirmed endometriosis at laparoscopy while 52 did not. Blood specimens were run in batches of 14 including four quality control samples for toxicological analysis. Each PCB congener was adjusted for recovery; batch-specific reagent blanks were subtracted. All PCB concentrations were log transformed and expressed in ng/g serum first as a sum and then as tertiles by purported estrogenic or anti-estrogenic activity of PCB congeners.

RESULTS

Using unconditional logistic regression analysis, a significantly elevated odds ratio (OR) was observed for women in the third tertile of anti-estrogenic PCBs [OR 3.77; 95% confidence interval (CI) 1.12-12.68]. Risk remained elevated after controlling for gravidity, current cigarette smoking and serum lipids (OR 3.30; 95% CI 0.87-12.46).

CONCLUSIONS

These data suggest that anti-estrogenic PCBs may be associated with the development of endometriosis.