Time-to-Pregnancy

BackgroundPolychlorinated biphenyls (PCBs) remain ubiquitous environmental contaminants. Developmental exposures are suspected to impact reproduction. Analysis of mixtures of PCBs may be problematic as components have a complex correlation structure, and along with limited sample sizes, standard regression strategies are problematic. We compared the results of a novel, empirical method to those based on categorization of PCB compounds by (1) hypothesized biological activity previously proposed and widely applied, and (2) degree of ortho- substitution (mono, di, tri), in a study of the relation of maternal serum PCBs and daughter's time to pregnancy.MethodsWe measured PCBs in maternal serum samples collected in the early postpartum in 289 daughters in the Child Health and Development Studies birth cohort. We queried time to pregnancy in these daughters 28-31 years later. We applied a novel weighted quantile sum approach to find the bad-actor compounds in the PCB mixture found in maternal serum. The approach includes empirical estimation of the weights through a bootstrap step which accounts for the variation in the estimated weights.ResultsBootstrap analyses indicated the dominant functionality groups associated with longer TTP were the dioxin-like, anti-estrogenic group (average weight, 22%) and PCBs not previously classified by biological activity (54%). In contrast, the unclassified PCBs were not important in the association with shorter TTP, where the anti-estrogenic groups and the PB-inducers group played a more important role (60% and 23%, respectively). The highly chlorinated PCBs (average weight, 89%) were mostly associated with longer TTP; in contrast, the degree of chlorination was less discriminating for shorter TTP. Finally, PCB 56 was associated with the strongest relationship with TTP with a weight of 47%.ConclusionsOur empirical approach found some associations previously identified by two classification schemes, but also identified other bad actors. This empirical method can generate hypotheses about mixture effects and mechanisms and overcomes some of the limitations of standard regression techniques.

BackgroundPesticides have been associated with reproductive disorders, but there is limited research on pesticide exposures and human fertility.ObjectiveWe aimed to investigate the effects of preconception exposure to pesticides on time to pregnancy (TTP) and on infertility in a general population of couples planning to become pregnant in Shanghai, China.MethodA total of 615 women who were planning a pregnancy were enrolled before conception and were prospectively followed for 1 y to observe their TTP. Preconception pesticide exposures were assessed by measuring urinary metabolites of organophosphates (OPs) and pyrethroids (PYRs). Fecundability odds ratios (FORs) and odds ratios (ORs) of infertility were estimated using Cox and logistic regression models, respectively. All analyses were repeated after restricting the sample to nulliparous women (n=569).ResultsAfter adjusting for age, prepregnancy BMI, current smoking, education, annual household income, age at menarche, and two items from the Perceived Stress Scale (PSS-10), women in the highest quartile of diethylthiophosphate (DETP; an OP metabolite) had significantly longer TTP [adjusted FOR=0.68 (95% CI: 0.51, 0.92)] and increased infertility [adjusted OR=2.17 (95% CI: 1.19, 3.93)] compared with women in the lowest quartile. The highest versus lowest quartile of 3-phenoxybenzoic acid (3PBA; a PYR metabolite) was associated with longer TTP and infertility, with significant associations in nulliparous women [adjusted FOR=0.72 (95% CI: 0.53, 0.98); adjusted OR for infertility=2.03 (95% CI: 1.10, 3.74)].ConclusionOur study provides some of the first evidence that preconception OP and PYR exposures are associated with decreased fertility in Chinese couples. Given that OPs and PYRs are rapidly metabolized in humans, more studies are needed to confirm our findings. https://doi.org/10.1289/EHP2987.

BackgroundFertility in recent decades in European countries such as Norway, Spain or United Kingdom has declined, while in others such as Portugal, it has remained relatively constant, and in others such as Germany fertility rated have risen. The determinants of this change in reproductive pattern can be explained by the cultural, social, and economic changes that took place in our society. Objective: to identify the principal reasons and independent determinants associated with the postponement of motherhood and document any association between the time taken to achieve successful pregnancy and maternal age, as well as the level of anxiety of these women.MethodsAn observational study, including 326 women, was conducted in Spain with primiparous women, in which data was collected on sociodemographic, health, and pregnancy-related factors. Comparison of means (t-test or analysis of variance) and the analysis of covariance was used to estimate adjusted means for potential confounders.ResultsWomen in stable relationships became mothers at older ages (31.83±0.29) than those who were not (28.75±0.78) (pConclusionsMedical reasons were among those cited for delaying motherhood. The postponement of motherhood was associated with difficulty to achieve a successful pregnancy and a higher level of anxiety.

BACKGROUND: Dietary patterns rich in plant-based foods, fish, and healthier fats are reportedly beneficial for fertility, but forming generalizable recommendations has been hindered by the lack of studies examining dietary patterns and time-to-conception (TTC) in cohorts with different ethnicities across geographical regions. To study the association of preconception dietary patterns with TTC in the multi-country NiPPeR trial. METHODS: This study is a secondary analysis of data collected in the NiPPeR randomized controlled trial. Women planning to conceive, without known fertility impairment, were recruited from the community in the UK, Singapore, and New Zealand (NZ). Dietary intake was assessed at preconception prior randomization, and across-site (“pooled”) data-driven dietary patterns were derived (n = 1406). TTC, derived as the number of days between recruitment and the estimated date of achieving a clinical pregnancy, and the chance of achieving a clinical pregnancy within a year, expressed as hazard ratios (HR), were analyzed using Cox proportional hazards models adjusted for preconception body mass index, age and gravidity. RESULTS: Two pooled dietary patterns were identified: “Vegetables, Fruits and Nuts” (VFN), and “Fried potatoes, Processed meat and Sweetened beverages” (FPS). Compared with the lowest quartile of VFN score, those in the highest quartile took a shorter time to conceive [Days till 20% conceived (95% CI): 73.0 (60.6, 91.5) vs 166.5 (120.0, 229.5)], and showed a higher chance of conception within a year [HR (95% CI): 2.15 (1.66, 2.78)]. This difference was most evident in Singapore, where the overall adherence to a VFN diet was substantially lower than in the UK and NZ [median (IQR) VFN score (expressed as standard deviation scores): Singapore -0.88 (-1.11, -0.57), UK 0.45 (0.07, 0.92), NZ 0.47 (-0.02, 0.90)]. There was no association between the FPS diet and TTC in the cohort. CONCLUSION: Consuming a diet rich in vegetables, fruits and nuts may shorten TTC and improve the chances of conception, particularly in populations with low intakes of such foods. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, identifier: NCT02509988, Universal Trial Number U1111-1171–8056. Registered on 16 July 2015.