Environment And Reproductive Health Research Articles

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

BackgroundPhthalates 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. MethodsParticipants (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. ResultsMetabolic 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. ConclusionOur 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.

Validation and measurement properties of the Male and Female Fertility Knowledge Inventories (MFKI and FFKI) in Iranian couples

BackgroundOne of the most important population challenges during the last three decades has been the significant decrease in the fertility rate worldwide. Since the validity and reliability of the Male and Female Fertility Knowledge Inventories (MFKI and FFKI) have not been determined in Iran, we conducted this study to assess psychometric characteristics of the MFKI and FFKI in couples in Tabriz and Urmia, Iran.MethodsThis was a cross-sectional study, as the first part (quantitative phase) of a sequential explanatory mixed-method study. The current study was done on 1200 participants (600 women with their husbands) living in the northwestern region of Iran, between January 2023 and September 2023. The psychometric properties of the Persian version of the tool (MFKI and FFKI) were performed in 5 stages, including translation process, content validity, face validity, construct validity and reliability assesment.ResultsIn this study, the CVI, CVR, and impact scores of the MFKI tool were equal to 0.90, 0.88, 3.26 and CVI, CVR, and Impact scores of the FFKI tool were respectively equal to 0.95, 0.91 and 3.59, that it indicated a satisfactory level of content and face validity. Then, to check the construct validity, the results of the exploratory factor analysis of the MFKI tool on 13 items led to the identification of 3 factors, including Environment and reproductive health (ERH), Lifestyle factors (LSF) and Sperm quality (SQ), which explained 66% of the cumulative variance. The results of the exploratory factor analysis of the FFKI tool on 15 items led to the identification of 4 factors, including Reproductive health (RH), Lifestyle factors (LSF), Chance of conception (CHC) and Ovarian reserve and preservation (ORP), which explained 68% of the cumulative variance.ConclusionsThe findings of this study indicated that the Persian version of MFKI and FFKI has acceptable psychometric properties to measure the awareness of Iranian couples regarding fertility, which can be used as a screening tool for fertility knowledge by health care professionals and also as a reliable tool in research.

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

BackgroundEpidemiologic 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. ObjectiveWe investigated whether maternal and paternal preconception and maternal pregnancy urinary phthalate metabolite and bisphenol A (BPA) concentrations were associated with child behavior. MethodsWe 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). ResultsThis 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). ConclusionIn 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.

P-585 Iron intake in relation to ovarian reserve among women seeking infertility treatment

Abstract Study question Is there an association between iron intake and ovarian reserve among women seeking fertility care? Summary answer Supplemental iron intake above 45mg/d is associated with lower ovarian reserve among women seeking fertility care. What is known already Although the literature regarding iron intake in relation to ovarian reserve is scant and inconsistent, some evidence suggest that iron may have gonadotoxic effects. Study design, size, duration Observational study including 582 female participants attending the Massachusetts General Hospital Fertility Center (2007–2019) enrolled in the Environment and Reproductive Health (EARTH) Study Participants/materials, setting, methods Iron intake was estimated using a validated food frequency questionnaire (FFQ). Markers of ovarian reserve included antral follicle count (AFC) (assessed via transvaginal ultrasound) and day 3 FSH, both obtained during the course of infertility evaluation. The association between iron intake and ovarian reserve was evaluated using Poisson regression models for AFC and quantile regression models for day 3 FSH adjusted for age, menstrual cycle characteristics, physical activity, carbohydrate intake and total energy intake. Main results and the role of chance Participants had a median age of 35 years and median total iron intake of 29 mg/d. Total iron intake was inversely related to AFC and this association was driven by intake of supplemental iron. Compared to women with a supplemental iron intake ≤20mg/day, women consuming 45-64mg/d of supplemental iron had a 17% (-35%, 0.3%) lower AFC and women consuming ≥65mg/d of supplemental iron had a 32% (-54%, -11%) lower AFC after adjusting for potential confounders (p, linear trend=0.003). Similarly, in multivariable-adjusted analysis, day 3 FSH levels were 0.9 (0.5, 1.3) IU/mL higher among women with a supplemental iron intake ≥65mg/d when compared to women with a supplemental iron intake ≤20mg/d (p, linear trend=0.02). Limitations, reasons for caution Iron intake was estimated using a method that relies on self-report and we had no biomarkers of iron status in our participants. Also, only 36 women consumed ≥45mg/d of supplemental iron. Wider implications of the findings Since all study participants were seeking fertility treatment, our findings may not apply to women in the general population. Although our findings are consistent with studies of women with iron overload, given the paucity of literature on this topic it is essential that this question is revisited in future studies. Trial registration number Not applicable, not a randomized trial

P-647 Intake of soy foods and soy isoflavones in relation to ovarian reserve among women presenting to a fertility center

Abstract Study question Are soy food and isoflavone intakes associated with ovarian reserve as measured by antral follicle count (AFC)? Summary answer Within the observed range of intake, soy food or isoflavone consumptions are not associated with AFC. What is known already Phytoestrogens are structurally similar to 17β-estradiol, and bind to ER-α and ER-β in vitro resulting in weak estrogenic activity. Previous work in ruminants, felines and rodents has shown that exposure to phytoestrogens can have major adverse impacts on reproduction. However, findings of studies in humans suggest that soy foods and soy phytoestrogens may not have major deleterious impacts on reproductive hormone levels or reproductive outcomes, and could even be beneficial in couples undergoing infertility treatment. Study design, size, duration Women presenting to a large academic fertility center between April 2007 and December 2019 were invited to participate in the Environment and Reproductive Health (EARTH) Study, a prospective cohort study. Intake of 15 soy-based foods during the previous three months was obtained at baseline and intake of soy phytoestrogens was estimated from these reports. AFC was assessed with transvaginal ultrasound performed as part of diagnostic evaluation for infertility. Participants/materials, setting, methods We included 667 women who reported their soy food intake and had an AFC assessment. Women were divided in groups of increasing soy food and soy isoflavone intake with women who reported not consuming soy-based foods serving as the reference group. We evaluated the association of soy foods and soy isoflavones intake with AFC using Poisson regression models adjusting for confounders. Analyses were also stratified by age, BMI, and smoking status. Main results and the role of chance Women had median baseline age of 35.0 years and BMI of 23.4 kg/m2. Mean (range) intake of soy foods was 0.1 (0-7.4) servings/day, and mean (range) intake of isoflavones was 6 (0-166) mg/day, which is comparable to that of women in the general population of the USA. Intakes of soy foods or isoflavones were not related to AFC. The median (IQR) AFC for women who did not consume soy foods and women in the highest category of soy intake (&amp;gt;0.45 servings/day, median 0.88 servings/day) were 12 (9, 18) and 13 (9, 19). After adjustment for potential confounders, the mean difference in AFC between women in the highest category of soy intake and women who did not consume soy was -0.5% (-6.6%, 6.1%). Soy food intake remained unrelated to AFC when intake was categorized using different cutoff values when intake was modeled as a continuous variable when departures from a linear association were considered, and when we excluded from analysis 76 women whose AFC ultrasound scan was performed before they completed the diet assessment. Soy intake was also unrelated to AFC within categories of age, BMI and smoking status. Findings for soy isoflavones mirrored those for soy-food intake. Limitations, reasons for caution Self-reported soy intake may have resulted in measurement error leading to attenuation of observed relations towards the null. Also, all participants were women presenting to a fertility center and therefore, findings may not be generalizable to women in the general population. Wider implications of the findings Our findings suggest soy food and isoflavone intakes within the ranges observed among women in the general population of the USA is unlikely to influence ovarian reserve in any meaningful way. Trial registration number Not applicable

Association of Urinary Phthalate and Phthalate Replacement Metabolite Concentrations with Serum Lipid Biomarker Levels among Pregnant Women Attending a Fertility Center.

We examined whether urinary concentrations of phthalate and phthalate replacement metabolites were associated with lipid biomarker levels among pregnant women. This cross-sectional study included 175 women who enrolled in the Environment and Reproductive Health (EARTH) Study (2005–2017). We used linear regression models to assess the relationship between urinary phthalates and lipid biomarkers [triglycerides, total cholesterol, high density lipoprotein (HDL), non-HDL, and low-density lipoprotein (LDL) cholesterol] levels while adjusting for confounders. Pregnant women in the highest quartile of urinary mono(2-ethyl-5-carboxypentyl) phthalate (MECPP) had, overall, 14% [31 (95% CI = 6.56) mg/dL], 21% [33 (95% CI = 9.57) mg/dL] and 25% [30 (95% CI = 8.53) mg/dL] higher serum total, non-HDL and LDL cholesterol, respectively, compared to women in the lowest quartile of MECPP. Similar positive associations were found for urinary concentrations of other metabolites of di(2-ethylhexyl) phthalate, mono(2-ethylhexyl) phthalate, and mono(2-ethyl-5-oxohexyl) phthalate. Pregnant women with urinary mono-n-butyl phthalate (MBP) in the highest quartile had higher triglycerides and non-HDL cholesterol compared to women with MBP in the lowest quartile. Women with detectable concentrations of two phthalate replacement metabolites had lower HDL cholesterol compared to women with non-detectable concentrations. Gestational urinary concentrations of certain phthalate and phthalate replacement metabolites were associated with lipid levels among these women.

Associations between mixtures of urinary phthalate metabolite concentrations and oxidative stress biomarkers among couples undergoing fertility treatment

Phthalate exposure has been associated with adverse reproductive outcomes and oxidative stress is a potential mechanism by which they act. However, few human studies have explored co-exposure confounding or joint effects. Furthermore, most studies examine associations between biomarkers of exposure and oxidative stress from the same urine sample. We investigated single-exposure, co-exposure-adjusted, and joint associations between phthalate metabolites and oxidative stress in the Environment and Reproductive Health (EARTH) study among couples undergoing fertility treatment. We examined cross-sectional associations in both women and men, and longitudinal associations in women. Urine was collected in the follicular phase (women only) and at the time of fertility procedure (women and men), and analyzed for 11 phthalate metabolites. Urine from the time of fertility procedure was analyzed for oxidative stress biomarkers, including free 8-iso-prostaglandin F2α (8-iso-PGF2α), its primary metabolite (2,3-dinor-5,6-dihydro-15-F2t-isoprostane [F2-IsoP-M]), and prostaglandin F2α (PGF2α). Linear mixed effects models were used to estimate single-exposure associations. Bayesian Kernel Machine Regression (BKMR) was used to adjust for co-exposures and to estimate joint effects. Among women, we observed positive associations between all phthalate metabolites and oxidative stress biomarkers in single-exposure models, but there was clear co-exposure confounding. For instance, in a single-exposure model, we estimated a 63% (95% confidence interval: 51, 77) increase in the 8-iso-PGF2α metabolite per interquartile range (IQR) difference in mono-n-butyl phthalate (MBP) versus a 34% (95% credible interval: 12, 60) increase in co-adjusted models. However, several phthalate metabolites remained associated with oxidative stress in co-exposure models, and the joint effects of all exposures were high (e.g., an 114% increase in the 8-iso-PGF2α metabolite per IQR difference in all exposures). Longitudinal results were also attenuated compared to cross-sectional results in women; however, the joint effect of all exposures and the 8-iso-PGF2α metabolite remained positive and statistically significant (11% increase per IQR difference in all exposures, 95% credible interval: 0.2, 23). In men, associations were generally less pronounced, although the joint effect of the mixture on 8-iso-PGF2α was above the null. Because oxidative stress is related to reproductive success among couples seeking fertility treatment, mitigating phthalate exposure should be considered as a potentially beneficial measure.

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.

Urinary phthalate metabolite concentrations are negatively associated with follicular fluid anti-müllerian hormone concentrations in women undergoing fertility treatment.

Exposure to phthalates, endocrine-disrupting chemicals commonly used as plasticizers and in consumer products, has been associated with infertility and premature ovarian failure. Our objective was to investigate whether urinary phthalate metabolite concentrations were associated with pre-ovulatory follicular fluid (FF) anti-müllerian hormone (AMH) concentrations in women undergoing fertility treatment. This cross-sectional analysis included 138 women with urinary phthalate data available in the Environment and Reproductive Health (EARTH) Study (2010-2016) in whom FF AMH concentrations were quantified using a sandwich enzyme-linked immunosorbent assay (ELISA). We also quantified 8 phthalate metabolite concentrations using tandem mass spectrometry in 1-2 urine samples per cycle (total 331 urines) and calculated the cycle-specific geometric mean for each metabolite. We applied cluster-weighted generalized estimating equation models (CWGEE) to evaluate the associations of tertiles of urinary phthalate metabolite concentrations with log-transformed FF AMH concentrations adjusting for potential confounders. Study participants had median age of 34.0years (IQR 32.0, 37.0), 83% were white, and median BMI of 23.1kg/m2 (IQR 21.2, 26.1). The following stimulation protocols were used: luteal phase agonist (70%), antagonist (14%), or flare (16%). Urinary concentrations of select phthalate metabolites were negatively associated with FF AMH. For example, women whose urinary mEOHP was in the lowest tertile (range 0.30-4.04ng/ml) had an adjusted mean FF AMH of 0.72ng/mL (95% CI=0.36, 1.44), compared to women in the highest tertile (range 9.90-235), who had an adjusted mean of 0.24ng/mL (95% CI=0.12-0.48, p<0.05). The negative association between urinary concentrations of certain phthalate metabolites with FF AMH concentrations may have implications for antral follicle recruitment and fertility treatment outcomes.

Parental Preconception and Prenatal Environmental Exposures and Child Neurobehavioral Outcomes

BACKGROUND AND AIM: There are limited studies quantifying the effects of paternal and maternal preconception environmental exposures on children’s health. The Preconception Environmental exposure And Childhood health Effects (PEACE) Study includes children (age 6-13 years) who were born to couples in the Environment and Reproductive Health (EARTH) Study and aims to determine the extent to which maternal and paternal preconception phthalate exposures are associated with neurobehavioral outcomes. METHODS: The PEACE study began in 2019 and is ongoing. A total of 478 eligible children (includes multiples) were born to 451 mothers who participated in the EARTH study (2005-2017). Study staff collected multiple maternal and paternal preconception urine samples before pregnancy and prenatal maternal urine samples during each trimester of pregnancy. We quantified 10 urinary phthalate metabolites in these samples. Children’s behavior, executive function, and reciprocal social behaviors are being assessed via parent-report using the Behavior Assessment System for Children-3 (BASC-3), Behavior Rating Inventory of Executive Function (BRIEF), and Social Responsiveness Scale-2 (SRS-2), respectively. Trained staff collected additional information about diet, sleep, physical activity, product use, and COVID-19 stress. RESULTS:As of March 2021, we enrolled 95 mothers, 57 fathers, and 120 children in the PEACE Study who completed visits either in person or virtually. Of children who completed the study, 64 (53%) were boys and 97 (81%) were White. Mean BASC-3 total behavior problem scores were 48.7 (SD: 7.6). Ten percent of children had scores indicative of being at-risk for behavioral problems (T-score60). Average BRIEF and SRS-2 scores were 48.2 (SD: 9.5) and 46.9 (SD:6.1), respectively. CONCLUSIONS:The PEACE Study will provide new information about the potential impact of parental preconception environmental chemical exposures on children’s health. In addition, the PEACE study will be able to leverage the rich data repository that includes parental chemical, built environment, and dietary exposures. KEYWORDS: Children's environmental health, Neurodevelopmental outcomes, Phthalates, Male, Chemical exposures, Endocrine disrupting chemicals, Female

P–106 The evaluation of dietary score representing the overall effect of men’s diet to semen quality on couple’s fertility

Abstract Study question Is men’s diet associated with assisted reproductive technology (ART) outcomes? Summary answer An empirical dietary score representing the overall effect of men’s diet on semen quality was unrelated to ART outcomes. What is known already Multiple studies have related various aspects of men’s diet to semen quality. Generally, healthier foods, such as fish, vegetables, and fruits, have been related to better semen quality, whereas unhealthy foods, like processed and red meats, have had the opposite relationship. Nevertheless, while bulk semen parameters are important biomarkers of male fertility and a diagnostic cornerstone for male factor infertility, they are imperfect predictors of a couple’s fertility. Study design, size, duration Couples presenting to the Massachusetts General Hospital Fertility Center between April 2007 and April 2018 were invited to participate in the Environment and Reproductive Health (EARTH) study, a prospective cohort study. Men’s diet was assessed with a previously validated food frequency questionnaire. A dietary score reflecting the overall relation of men’s food intake with semen quality parameters was empirically derived using reduced rank regression (RRR). The resulting dietary score was related to ART outcomes. Participants/materials, setting, methods We used information from 349 men (908 semen samples) to derive the empirical diet pattern and data from 231 couples (407 ART cycles). The primary outcome was the probability of live birth per treatment cycle; secondary outcomes were semen quality, and fertilization, implantation, and clinical pregnancy rates. We evaluated the association between the dietary score and these outcomes using logistic generalized linear mixed models to account for repeated cycles while adjusting for confounders. Main results and the role of chance Men had a median baseline age and BMI of 36.8 years and 26.9 kg/m2, respectively. The empirical diet pattern was significantly associated with all semen parameters. One standard deviation increase in the empirical diet pattern was associated with lower volume (–0.10 standard units [95% CI: –0.17 to –0.04]) and to higher sperm total sperm count (0.13 standard units [0.06 to 0.20]), concentration (0.17 standard units [0.10 to 0.24]), total motility (0.14 standard units [0.07 to 0.20]), progressive motility (0.08 standard units [0.01 to 0.15]), and normal morphology (0.18 standard units [0.11 to 0.25]). Couples with men in the lowest quartile of the empirical score were more likely to have a diagnosis of male infertility than couples with men in the highest quartile (49% vs 24%). Despite the association with semen parameters, the empirical diet score was not related to any clinical outcome of infertility treatment with ART. The adjusted probabilities of implantation, clinical pregnancy and live birth in the lowest and highest quartile of the empirical score were 0.62 (0.50–0.73) and 0.55 (0.45–0.66), 0.57 (0.46–0.69) and 0.50 (0.40–0.61), and 0.49 (0.37–0.62) and 0.36 (0.25–0.48), respectively. Analyses excluding couples with a diagnosis of male factor infertility yielded similar results. Limitations, reasons for caution We evaluated the relationship only among couples presenting to a fertility center and therefore it is unclear whether findings can be generalized to couples trying to conceive without ART. Wider implications of the findings: Given ART is a robust intervention including stringent sperm selection procedures, any effect that empirical diet may have on a couple’s chances of conceiving through assisted reproduction is unlikely to reflect the effect of these factors on bulk semen quality parameters. Trial registration number The project was funded by ES009718, ES022955, ES026648, and ES000002 from the National Institute of Environmental Health Sciences, and P30DK46200 from the National Institute of Diabetes and Digestive and Kidney Diseases

Parental preconception exposure to phenol and phthalate mixtures and the risk of preterm birth

BackgroundParental preconception exposure to select phenols and phthalates was previously associated with increased risk of preterm birth in single chemical analyses. However, the joint effect of phenol and phthalate mixtures on preterm birth is unknown. MethodsWe included 384 female and 211 male (203 couples) participants seeking infertility treatment in the Environment and Reproductive Health (EARTH) Study who gave birth to 384 singleton infants between 2005 and 2018. Mean preconception urinary concentrations of bisphenol A (BPA), parabens, and eleven phthalate biomarkers, including di(2-ethylhexyl) phthalate (DEHP) metabolites, were examined. We used principal component analysis (PCA) with log-Poisson regression and Probit Bayesian Kernel Machine Regression (BKMR) with hierarchical variable selection to examine maternal and paternal phenol and phthalate mixtures in relation to preterm birth. Couple-based BKMR model was fit to assess couples’ joint mixtures in relation to preterm birth. ResultsPCA identified the same four factors for maternal and paternal preconception mixtures. Each unit increase in PCA scores of maternal (adjusted Risk Ratio (aRR): 1.36, 95%CI: 1.00, 1.84) and paternal (aRR: 1.47, 95%CI: 0.90, 2.42) preconception DEHP-BPA factor was positively associated with preterm birth. Maternal and paternal BKMR models consistently presented the DEHP-BPA factor with the highest group Posterior Inclusion Probability (PIP). BKMR models further showed that maternal preconception BPA and mono(2-ethyl-5-hydroxyhexyl) phthalate, and paternal preconception mono(2-ethylhexyl) phthalate were positively associated with preterm birth when the remaining mixture components were held at their median concentrations. Couple-based BKMR models showed a similar relative contribution of paternal (PIP: 61%) and maternal (PIP: 77%) preconception mixtures on preterm birth. We found a positive joint effect on preterm birth across increasing quantiles of couples’ total mixture concentrations. ConclusionIn this prospective cohort of subfertile couples, maternal BPA and DEHP, and paternal DEHP exposure before conception were positively associated with preterm birth. Both parental windows jointly contributed to the outcome. These results suggest that preterm birth may be a couple-based pregnancy outcome.

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

BackgroundExposure 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. ObjectiveWe 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. MethodsWe 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. ResultsDuring 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. ConclusionWe 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.

Parental Preconception Phenol and Phthalate Mixtures in Relation to Birth Weight

Background: Although maternal and paternal preconception exposures to some phenols and phthalates have been associated with reduced birthweight in single-chemical analyses, their effect in the context of complex mixtures is unknown. Methods: We used principal component analysis (PCA) with multivariable linear regression and Bayesian Kernel Machine Regression (BKMR) to examine maternal and paternal preconception mixtures of urinary concentrations of phenol and phthalate biomarkers in relation to birthweight among 384 singletons (384 mothers, 211 fathers, 203 couples) from the Environment and Reproductive Health (EARTH) Study, a prospective cohort of couples seeking fertility evaluation. We also fit couple-based BKMR with hierarchical variable selection to assess couples’ joint mixtures in relation to birthweight. Natural log-concentrations of bisphenol A (BPA), parabens, and eleven phthalate metabolites including those of di(2-ethylhexyl) phthalate (DEHP) were examined. Birthweight was abstracted from medical records. Results: The PCA identified the same four main factors for maternal and paternal preconception mixtures. Each 1-unit increase in PCA scores of maternal (-51g; 95%: -105, 2) and paternal (-73g; 95%CI: -141, -4) preconception low molecular weight phthalates factors, and paternal preconception DEHP-BPA factor (-63g; 95%CI: -134, 7) were associated with reduced birthweight. In BKMR models of individual biomarkers, we found that maternal preconception monoethyl phthalate and BPA, and paternal preconception mono-n-butyl phthalate were inversely associated with birthweight when the remaining mixture components were held at their median concentration. In couple-based BKMR models, we observed a negative joint effect on birthweight across increasing quantiles of couples’ total phenol and phthalate mixture concentration. Paternal preconception biomarkers contributed more to couples’ joint effect on birthweight (Posterior Inclusion Probability (PIP)=70%) compared with maternal preconception biomarkers (PIP=18%). Conclusions: Our analysis suggests a complex interplay between paternal and maternal preconception exposure to mixtures of non-persistent chemicals, with both parental windows of exposure independently and jointly contributing to reduced birthweight.

Associations between urinary phthalate metabolite mixtures and oxidative stress biomarkers among male partners of couples undergoing fertility treatments

Background: Oxidative stress, the imbalance between reactive oxygen species and antioxidants, has been associated with sperm dysfunction in men. Phthalate exposure has been associated with increased oxidative stress; however, few studies have explored the joint association between exposure to multiple phthalate metabolites simultaneously and circulating oxidative stress measures. Methods: We addressed this question among men (n=235) in the Environment and Reproductive Health (EARTH) study, in which couples seeking infertility treatment were recruited from a clinic in Boston, MA, USA. For males, one urine sample was collected for each fertility treatment cycle. Samples were analyzed for a panel of 11 phthalate metabolites and 3 oxidative stress biomarkers, including 8-iso-prostaglandin F2α [8isoPGF2a], its primary metabolite, and prostaglandin F2α. All measures were corrected for specific gravity to account for urine dilution, and all estimates were adjusted for potential confounders and accounted for repeated exposure and outcome measures. Single pollutant models for each phthalate metabolite and oxidative stress marker were created using linear mixed effects models. The joint association with the overall mixture was assessed using Bayesian Kernel Machine Regression (BKMR). Results: In single pollutant models, most phthalate metabolites were associated with increases in 8isoPGF2a, but not other oxidative stress markers. For example, an interquartile range increase (IQR) in summed di-2-ethylhexyl phthalate metabolites was associated with a 7.5% (95% CI: 2.0% – 13.4%) increase in 8isoPGF2a. The BKMR model also demonstrated a 20.4% (95% credible interval: 8.8% – 33.2%) increase in the 8isoPGF2a concentration per a joint increase in all phthalate metabolites from the 1st to the 3rd quartile. Conclusions: Among men presenting at an infertility clinic, those with higher overall urinary concentrations of phthalate metabolites had elevated urinary 8isoPGF2a levels, indicative of oxidative stress or inflammation. This mechanism could be relevant to previously observed associations between phthalate metabolites and fertility measures in men.

Development and Testing of Response Surface Methods for Investigating the Epidemiology of Exposures to Mixtures

We are extending Bayesian kernel machine regression (bkmr) to examine health outcomes as a function of a multi-dimensional space of exposures, adding capabilities needed by environmental epidemiologists such as mediation, multiple imputation and the ability to analyze large data sets. Borrowing ideas from toxicology, we are developing an approach related to bkmr that constructs exposure summary scores and tests when they are appropriate, an important goal for mixtures epidemiology. We are testing bkmr and other other mixtures methods and comparing results using both synthetic data and real world data sets, including the Environment And Reproductive Health (EARTH) Study.A second focus of our project is the application of causal models to mixtures epidemiology, including the construction of synthetic data sets and interpretation of results. We have extended our earlier analysis of co-exposure amplification bias to methods in addition to regular linear regression. Special care in causal methods must be used when constructing synthetic data sets with increasing correlation between exposures.

Follicular fluid anti-Müllerian hormone (AMH) concentrations and outcomes of in vitro fertilization cycles with fresh embryo transfer among women at a fertility center.

To enhance the understanding of the clinical significance of anti-Müllerian hormone (AMH) in follicular fluid, we aimed to determine the variability of AMH concentrations in follicular fluid within and across IVF cycles and whether high follicular fluid AMH concentrations are associated with improved clinical IVF outcomes. This was a retrospective cohort study of companion follicular fluid and serum samples from 162 women enrolled in the Environment and Reproductive Health (EARTH) Study between 2010 and 2016. AMH concentrations were quantified using a sandwich enzyme-linked immunosorbent assay. Spearman correlation and intra-class correlation (ICC) were calculated to assess variability of follicular fluid AMH, and generalized linear mixed models were used to evaluate the associations of FF AMH with IVF outcomes. The median (interquartile range, IQR) age of the 162 women was 34.0years (32.0, 37.0). Follicular fluid AMH concentrations were highly correlated between follicles within each IVF cycle (Spearman r = 0.78 to 0.86) and across cycles for each woman (ICC 0.87 (95% CI 0.81 to 0.92)). Compared with women in the highest tertile of FF AMH (mean AMH = 2.3ng/ml), women in the lowest tertile (mean AMH = 0.2ng/ml) had lower serum AMH (T1 = 0.1ng/ml vs. T3 = 0.6ng/ml, p < 0.0001). In adjusted models, higher tertiles of follicular fluid AMH concentrations were associated with lower mean endometrial thickness and higher probability of clinical pregnancy. Follicular fluid AMH concentrations show little variability between pre-ovulatory follicles, and higher pre-ovulatory follicular fluid AMH may predict a higher probability of clinical pregnancy.

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 (, ) and triiodothyronine (, ), 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 , , , and [absolute difference: ; 95% confidence interval (CI): , ; ; absolute difference: ; 95% CI: , ; ; absolute difference: ; 95% CI: 0.54, ; ; and absolute difference: ; 95% CI: , ; , 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

Maternal and paternal preconception exposure to phenols and preterm birth

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

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

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. 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. 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.