Maternal Urinary Fluoride and Child Neurobehavior at Age 36 Months

Importance

Recent studies in Canadian and Mexican populations suggest an association of higher prenatal fluoride exposure with poorer neurobehavioral development, but whether this association holds for US-based populations is unknown.

Objective

To examine associations of third trimester maternal urinary fluoride (MUF) with child neurobehavior at age 3 years in the US.

Design, Setting, and Participants

This prospective cohort study utilized urine samples archived from 2017 to 2020 and neurobehavioral data assessed from 2020 to 2023 from the Maternal and Developmental Risks from Environmental and Social Stressors (MADRES) pregnancy cohort, which consisted of predominately Hispanic women residing in Los Angeles, California. Cohort eligibility criteria at recruitment included being 18 years of age or older, less than 30 weeks' gestation, and a fluent English or Spanish speaker. Exclusion criteria included having a disability preventing participation or provision of informed consent, being HIV positive or incarcerated, and having a multiple gestation pregnancy. There were 263 mother-child pairs who completed the 3-year study visit. In this analysis, women who reported prenatal smoking were excluded. Data analysis was conducted from October 2022 to March 2024.

Exposure

Specific gravity-adjusted MUF (MUFSG), a biomarker of prenatal fluoride exposure.

Main Outcomes and Measures

Neurobehavior was quantified using the Preschool Child Behavior Checklist (CBCL), which included composite scores for Total Problems, Internalizing Problems, and Externalizing Problems. CBCL composite T scores range from 28 to 100. T scores from 60 to 63 are in the borderline clinical range, whereas scores above 63 are in the clinical range. Linear and logistic regression models adjusted for covariates were conducted.

Results

A total of 229 mother-child pairs (mean [SD] maternal age, 29.45 [5.67] years; 116 female children [50.7%] and 113 male children [49.3%]) who had MUFSG measured were included in the study. Median (IQR) MUFSG was 0.76 (0.51-1.19) mg/L, and 32 participants (14.0%) had a Total Problems T score in the borderline clinical or clinical range. A 1-IQR (0.68 mg/L) increase in MUFSG was associated with nearly double the odds of the Total Problems T score being in the borderline clinical or clinical range (odds ratio, 1.83; 95% CI, 1.17-2.86; P = .008), as well as with a 2.29-point increase in T score for the Internalizing Problems composite (B = 2.29; 95% CI, 0.47-4.11; P = .01) and a 2.14-point increase in T score for the Total Problems composite (B = 2.14; 95% CI, 0.29-3.98; P = .02).

Conclusions and Relevance

In this prospective cohort study of mother-child pairs in Los Angeles, California, prenatal fluoride exposure was associated with increased neurobehavioral problems. These findings suggest that there may be a need to establish recommendations for limiting fluoride exposure during the prenatal period.

Prenatal exposures to organophosphate ester metabolites and early motor development in the MADRES cohort

Organophosphate esters (OPEs) are increasingly considered neurotoxicants which may impact gross and fine motor development. We evaluated associations between prenatal OPE exposures and infant motor development. Third trimester urinary concentrations of nine OPE metabolites were measured in 329 mother-infant dyads participating in the Maternal And Developmental Risks from Environmental and Social Stressors (MADRES) cohort. Child gross and fine motor development at 6, 9, 12, and 18-months were assessed with the Ages and Stages Questionnaire-3 (ASQ-3) and operationalized in models using dichotomous instrument-specific cutoffs for typical motor development. Five OPE metabolites with >60% detection were specific-gravity-adjusted, natural log-transformed, and modeled continuously, while four metabolites with <60% detection were modeled dichotomously (detected/not-detected). We fit mixed effects logistic regression between OPE metabolites and fine/gross motor development and assessed sex-specific effects using a statistical interaction term and sex-stratified models. Among children, 31% and 23% had gross and fine motor scores, respectively, below the ASQ-3 at-risk cutoffs at least once across infancy. A doubling in prenatal diphenyl phosphate (DPHP) exposure was associated with 26% increased odds of potential fine motor delays (ORfine = 1.26, 95% CI: 1.02, 1.57, p = 0.04). We also observed significant interactions by infant sex for associations of detected dipropyl phosphate (DPRP) with gross motor development (pinteraction = 0.048) and detected bis(1-chloro-2-propyl) phosphate (BCIPP) with fine motor development (pinteraction = 0.02). Females had greater odds of potential motor delays for both detected DPRP (females vs males ORgross (95% CI) = 1.48 (0.71, 3.09), p = 0.30 vs 0.27 (0.06, 1.29), p = 0.10) and detected BCIPP (females vs males ORfine (95% CI) = 2.72 (1.27, 5.85), p = 0.01 vs 0.76 (0.31, 1.90), p = 0.56). There were no other significant associations between other metabolites and motor development, despite similar patterns. We found evidence of adverse effects of prenatal OPE exposures on infant motor development with greater adverse effects among female infants with some OPE metabolites.

Associations of Organophosphate Ester Flame Retardant Exposures during Pregnancy with Gestational Duration and Fetal Growth: The Environmental influences on Child Health Outcomes (ECHO) Program

BACKGROUND

Widespread exposure to organophosphate ester (OPE) flame retardants with potential reproductive toxicity raises concern regarding the impacts of gestational exposure on birth outcomes. Previous studies of prenatal OPE exposure and birth outcomes had limited sample sizes, with inconclusive results.

OBJECTIVES

We conducted a collaborative analysis of associations between gestational OPE exposures and adverse birth outcomes and tested whether associations were modified by sex.

METHODS

We included 6,646 pregnant participants from 16 cohorts in the Environmental influences on Child Health Outcomes (ECHO) Program. Nine OPE biomarkers were quantified in maternal urine samples collected primarily during the second and third trimester and modeled as log 2 -transformed continuous, categorized (high/low/nondetect), or dichotomous (detect/nondetect) variables depending on detection frequency. We used covariate-adjusted linear, logistic, and multinomial regression with generalized estimating equations, accounting for cohort-level clustering, to estimate associations of OPE biomarkers with gestational length and birth weight outcomes. Secondarily, we assessed effect modification by sex.

RESULTS

Three OPE biomarkers [diphenyl phosphate (DPHP), a composite of dibutyl phosphate and di-isobutyl phosphate (DBUP/DIBP), and bis(1,3-dichloro-2-propyl) phosphate] were detected in > 85 % of participants. In adjusted models, DBUP/DIBP [odds ratio (OR) per doubling = 1.07 ; 95% confidence interval (CI): 1.02, 1.12] and bis(butoxyethyl) phosphate (OR for high vs. nondetect = 1.25 ; 95% CI: 1.06, 1.46), but not other OPE biomarkers, were associated with higher odds of preterm birth. We observed effect modification by sex for associations of DPHP and high bis(2-chloroethyl) phosphate with completed gestational weeks and odds of preterm birth, with adverse associations among females. In addition, newborns of mothers with detectable bis(1-chloro-2-propyl) phosphate, bis(2-methylphenyl) phosphate, and dipropyl phosphate had higher birth weight-for-gestational-age z -scores (β for detect vs. nondetect = 0.04 - 0.07 ); other chemicals showed null associations.

DISCUSSION

In the largest study to date, we find gestational exposures to several OPEs are associated with earlier timing of birth, especially among female neonates, or with greater fetal growth. https://doi.org/10.1289/EHP13182.

Prenatal exposures to organophosphate ester metabolite mixtures and children's neurobehavioral outcomes in the MADRES pregnancy cohort

BACKGROUND

Evidence suggests organophosphate esters (OPEs) are neurotoxic; however, the epidemiological literature remains scarce. We investigated whether prenatal exposures to OPEs were associated with child neurobehavior in the MADRES cohort.

METHODS

We measured nine OPE metabolites in 204 maternal urine samples (gestational age at collection: 31.4 ± 1.8 weeks). Neurobehavior problems were assessed among 36-month-old children using the Child Behavior Checklist's (CBCL) three composite scales [internalizing, externalizing, and total problems]. We examined associations between tertiles of prenatal OPE metabolites (> 50% detection) and detect/non-detect categories (< 50% detection) and CBCL composite scales using linear regression and generalized additive models. We also examined mixtures for widely detected OPEs (n = 5) using Bayesian kernel machine regression.

RESULTS

Maternal participants with detectable versus non-detectable levels of bis(2-methylphenyl) phosphate (BMPP) had children with 42% (95% CI: 4%, 96%) higher externalizing, 45% (-2%, 114%) higher internalizing, and 35% (3%, 78%) higher total problems. Participants in the second versus first tertile of bis(butoxethyl) phosphate (BBOEP) had children with 43% (-1%, 109%) higher externalizing scores. Bis(1-chloro-2-propyl) phosphate (BCIPP) and child sex had a statistically significant interaction in internalizing (p = 0.02) and total problems (p = 0.03) models, with 120% (23%, 295%) and 57% (6%, 134%) higher scores in the third versus first BCIPP tertile among males. Among females, detectable vs non-detectable levels of prenatal BMPP were associated with 69% higher externalizing scores (5%, 170%) while the third versus first tertile of prenatal BBOEP was associated with 45% lower total problems (-68%, -6%). Although the metabolite mixture and each CBCL outcome had null associations, we observed marginal associations between di-n-butyl phosphate and di-isobutyl phosphate (DNBP + DIBP) and higher internalizing scores (0.15; 95% CrI: -0.02, 0.32), holding other metabolites at their median.

CONCLUSIONS

Our results generally suggest adverse and sex-specific effects of prenatal exposure to previously understudied OPEs on neurobehavioral outcomes in 36-month children, providing evidence of potential OPE neurotoxicity.

Sex-specific effects of prenatal organophosphate ester (OPE) metabolite mixtures and adverse infant birth outcomes in the maternal and developmental risks from environmental and social stressors (MADRES) pregnancy cohort

BACKGROUND

Organophosphate esters (OPEs) are used as flame retardants and plasticizers in various consumer products. Limited prior research suggests sex-specific effects of prenatal OPE exposures on fetal development. We evaluated overall and sex-specific associations between prenatal OPE exposures and gestational age (GA) at birth and birthweight for gestational age (BW for GA) z-scores among the predominately low-income, Hispanic MADRES cohort.

METHODS

Nine OPE metabolite concentrations were measured in 421 maternal urine samples collected during a third trimester visit (GA = 31.5 ± 2.0 weeks). We examined associations between single urinary OPE metabolites and GA at birth and BW for GA z-scores using linear regression models and Generalized Additive Models (GAMs) and effects from OPE mixtures using Bayesian Kernel Machine Regression (BKMR). We also assessed sex-specific differences in single metabolite analyses by evaluating statistical interactions and stratifying by sex.

RESULTS

We did not find significant associations between individual OPE metabolites and birth outcomes in the full infant sample; however, we found that higher bis(1,3-dichloro-2-propyl) phosphate (BDCIPP) was associated with earlier GA at birth among male infants (p = 0.04), and a nonlinear, inverted U-shape association between the sum of dibutyl phosphate and di-isobutyl phosphate (DNBP + DIBP) and GA at birth among female infants (p = 0.03). In mixtures analysis, higher OPE metabolite mixture exposures was associated with lower GA at birth, which was primarily driven by female infants. No associations were observed between OPE mixtures and BW for GA z-scores.

CONCLUSION

Higher BDCIPP and DNBP + DIBP concentrations were associated with earlier GA at birth among male and female infants, respectively. Higher exposure to OPE mixtures was associated with earlier GA at birth, particularly among female infants. However, we saw no associations between prenatal OPEs and BW for GA. Our results suggest sex-specific impacts of prenatal OPE exposures on GA at birth.

COVID-19 Pandemic Experiences and Symptoms of Pandemic-Associated Traumatic Stress Among Mothers in the US

Importance

The primary outcomes of the COVID-19 pandemic on the mental health of women with children remain largely unknown.

Objectives

To identify and describe clusters of mothers of children participating in the Environmental influences on Child Health Outcomes (ECHO) Program that characterize pandemic-associated hardships, coping mechanisms, and behaviors, and to evaluate associations between pandemic-associated hardships, coping strategies, and behavior changes with pandemic-associated traumatic stress symptoms.

Design, Setting, and Participants

This multicenter cohort study investigated experiences during the COVID-19 pandemic between April 2020 and August 2021 among maternal caregivers of children participating in the ECHO Program. Data from self-identified mothers of ECHO-enrolled children from 62 US cohorts were included in analyses. Data were analyzed from November 2021 to July 2022.

Exposures

The primary exposures were pandemic-associated changes in mothers' health, health care utilization, work and finances, coping strategies, and health-associated behaviors. Exposures were assessed via a self-reported questionnaire designed by ECHO investigators.

Main Outcomes and Measures

The primary outcome was the total symptoms score of pandemic-associated traumatic stress (PTS), defined as the number of items endorsed at least sometimes or more frequently, from a 10-item self-report measure.

Results

The study surveyed 11 473 mothers (mean [SD] age, 37.8 [7.4] years; 342 American Indian [2.98%], 378 Asian [3.29%], 1701 Black [14.83%], and 7195 White [62.71%]; 2184 with Hispanic/Latina ethnicity [19.04%]) and identified 2 clusters that best characterized their COVID-19 pandemic experiences-one characterized by higher life disruptions (eg, to work and health care), higher social isolation, more coping behaviors to mitigate the outcomes of the pandemic, and more changes to their health behavior routines (high change [1031 mothers]) and the other characterized by lower changes (low change [3061 mothers]). The high change cluster was more socioeconomically advantaged and reported higher PTS (mean [SD] number of symptoms, 3.72 [2.44] vs 2.51 [2.47]). Across both clusters, higher pandemic-associated hardships, coping mechanisms, and behavior changes were associated with higher PTS, and these associations were greater in the low change cluster.

Conclusions and Relevance

In this study of more than 11 000 US mothers, associations between socioeconomic factors, stressful life events, and mental health sequelae were complex. Accordingly, programs, policies, and practices targeting mental health during public health crises such as the COVID-19 pandemic should consider the range and configuration of hardships in designing the most effective interventions to mitigate long-term outcomes.

Perceived vulnerability to immigration policies among postpartum Hispanic/Latina women in the MADRES pregnancy cohort before and during the COVID-19 pandemic

INTRODUCTION AND OBJECTIVES

Research suggests that perceived immigration policy vulnerability has important health implications. Coupled with the mental and physical stressors accompanying the postpartum period and a growing awareness of the discrimination and structural racism experienced by marginalized communities globally, the coronavirus disease 2019 period may have exacerbated stress among vulnerable populations, specifically postpartum Hispanic/Latina women. This study evaluated perceived immigration policy vulnerability (i.e. discrimination, social isolation, and family threats) in early postpartum Hispanic/Latina women in Los Angeles before and during the coronavirus disease 2019 pandemic.

METHODS

The Perceived Immigration Policy Effects Scale (PIPES) was administered cross-sectionally at 1 month postpartum to 187 Hispanic/Latina women in the MADRES cohort. Respondents between September 2018 and March 2020 were classified as "pre-pandemic" (N = 128), between March 2020 and July 2020 as "early pandemic" (N = 38), and between August 2020 and November 2021 as "later pandemic" (N = 21). Average PIPES subscale scores were dichotomized into "higher" and "lower" groups (⩽median, >median) and logistic regression models were performed.

RESULTS

Approximately half of participants had incomes of <$50,000 (50.3%) and were Latin American born (54.6%). After adjusting for age, nativity, education, income, postpartum distress, and employment status, early pandemic respondents had 5.05 times the odds of a higher score on the perceived discrimination subscale (95% CI: 1.81, 14.11), 6.47 times the odds of a higher score on the social isolation subscale (95% CI: 2.23, 18.74), 2.66 times the odds of a higher score on the family threats subscale (95% CI: 0.97, 7.32), and 3.36 times the odds of a higher total score (95% CI: 1.19, 9.51) when compared to pre-pandemic respondents. There were no significant subscale score differences between later pandemic and pre-pandemic periods.

CONCLUSION

Higher perceived immigration policy vulnerability was reported among postpartum women during the early coronavirus disease 2019 pandemic versus pre-pandemic periods. This suggests greater social inequities during the early pandemic period.

Prenatal ambient air pollution and maternal depression at 12 months postpartum in the MADRES pregnancy cohort

BACKGROUND

Depression is the leading cause of mental health-related morbidity and affects twice as many women as men. Hispanic/Latina women in the US have unique risk factors for depression and they have lower utilization of mental health care services. Identifying modifiable risk factors for maternal depression, such as ambient air pollution, is an urgent public health priority. We aimed to determine whether prenatal exposure to ambient air pollutants was associated with maternal depression at 12 months after childbirth.

METHODS

One hundred eighty predominantly low-income Hispanic/Latina women participating in the ongoing MADRES cohort study in Los Angeles, CA were followed from early pregnancy through 12 months postpartum through a series of phone questionnaires and in-person study visits. Daily prenatal ambient pollutant estimates of nitrogen dioxide (NO2), ozone (O3), and particulate matter (PM10 and PM2.5) were assigned to participant residences using inverse-distance squared spatial interpolation from ambient monitoring data. Exposures were averaged for each trimester and across pregnancy. The primary outcome measure was maternal depression at 12 months postpartum, as reported on the 20-item Center for Epidemiologic Studies-Depression (CES-D) scale. We classified each participant as depressed (n = 29) or not depressed (n = 151) based on the suggested cutoff of 16 or above (possible scores range from 0 to 60) and fitted logistic regression models, adjusting for potential confounders.

RESULTS

We found over a two-fold increased odds of depression at 12 months postpartum associated with second trimester NO2 exposure (OR = 2.63, 95% CI: 1.41-4.89) and pregnancy average NO2 (OR = 2.04, 95% CI: 1.13-3.69). Higher second trimester PM2.5 exposure also was associated with increased depression at 12 months postpartum (OR = 1.56, 95% CI: 1.01-2.42). The effect for second trimester PM10 was similar and was borderline significant (OR = 1.58, 95% CI: 0.97-2.56).

CONCLUSIONS

In a low-income cohort consisting of primarily Hispanic/Latina women in urban Los Angeles, we found that prenatal ambient air pollution, especially mid-pregnancy NO2 and PM2.5, increased the risk of depression at 12 months after childbirth. These results underscore the need to better understand the contribution of modifiable environmental risk factors during potentially critical exposure periods.