Thinness and fecundability: Time to pregnancy after adolescent marriage in rural Bangladesh.

Undernutrition may affect fecundability, but few studies have quantified this relationship. In rural Bangladesh, where newlywed couples face strong pressures to become pregnant, we assessed fecundability, estimated by time to pregnancy (TTP), and its association with preconceptional thinness among nulligravid, newlywed female adolescents. During 2001-2002, 5,516 newlywed women aged 12-19 years participated in a home-based, 5-weekly surveillance system for 5-6 years to enrol pregnant women into an antenatal vitamin A or ß-carotene supplementation trial. Thinness was defined as a left mid-upper arm circumference (MUAC) ≤21.5 versus >21.5 cm. At each visit, staff obtained a monthly history of menstruation. Report of amenorrhea prompted a human chorionic gonadotropin urine test to confirm pregnancy. We derived hazard ratios (with 95% confidence intervals [CI]) for pregnancy and Kaplan-Meier curves for TTP. Ages of women at marriage and pregnancy detection (mean ± standard deviation) were 15.3 ± 1.9 and 17.0 ± 1.9 years, respectively. A total of 82.7% of thinner and 87.3% of better nourished women became pregnant. The unadjusted and multivariable relative hazard of ever becoming pregnant was 0.84 (95% CI [0.78, 0.89]) and 0.86 (95% CI [0.81, 0.92]), respectively, and TTP was 12 weeks longer (median [95% CI]: 63 [58-68] vs. 51 [49-54]) in women whose MUAC was ≤21.5 versus >21.5 cm. In rural Bangladesh, thin adolescent newlywed girls have a lower probability of becoming pregnant and experience a longer time to pregnancy.

First Trimester Urinary Bisphenol and Phthalate Concentrations and Time to Pregnancy: A Population-Based Cohort Analysis.

Background: Increasing evidence suggests that exposure to synthetic chemicals such as bisphenols and phthalates can influence fecundability. The current study describes associations of first trimester urinary concentrations of bisphenol A (BPA), BPA analogs, and phthalate metabolites with time to pregnancy (TTP). Methods: Among 877 participants in the population-based Generation R pregnancy cohort, we measured first trimester urinary concentrations of bisphenols and phthalates [median gestational age, 12.9 weeks (interquartile range, 12.1, 14.4)]. We used fitted covariate-adjusted Cox proportional hazard models to examine associations of bisphenol and phthalate concentrations with TTP. Participants who conceived using infertility treatment were censored at 12 months. Biologically plausible effect measure modification by folic acid supplement use was tested. Results: In the main models, bisphenol and phthalate compounds were not associated with fecundability. In stratified models, total bisphenols and phthalic acid were associated with longer TTP among women who did not use folic acid supplements preconceptionally [respective fecundability ratios per each natural log increase were 0.90 (95% CI, 0.81 to 1.00) and 0.88 (95% CI, 0.79 to 0.99)]. Using an interaction term for the exposure and folic acid supplement use showed additional effect measure modification by folic acid supplement use for high-molecular-weight phthalate metabolites. Conclusions: We found no associations of bisphenols and phthalates with fecundability. Preconception folic acid supplementation seems to modify effects of bisphenols and phthalates on fecundability. Folic acid supplements may protect against reduced fecundability among women exposed to these chemicals. Further studies are needed to replicate these findings and investigate potential mechanisms.

Higher urinary lignan concentrations in women but not men are positively associated with shorter time to pregnancy.

Phytoestrogens have been associated with subtle hormonal changes, although effects on fecundity are unknown. Our objective was to evaluate the association between male and female urinary phytoestrogen (isoflavone and lignan) concentrations and time to pregnancy (TTP) in a population-based cohort of 501 couples desiring pregnancy and discontinuing contraception. Couples were followed for 12 mo or until pregnancy. Fecundability ORs (FORs) and 95% CIs were estimated after adjusting for age, body mass index, race, site, creatinine, supplement use, and physical activity in relation to female, male, and joint couple concentrations. Models included the phytoestrogen of interest and the sum of the remaining individual phytoestrogens. FORs <1 denote a longer TTP and FORs >1 a shorter TTP. Urinary lignan concentrations were higher, on average, among female partners of couples who became pregnant during the study compared with women who did not become pregnant (median enterodiol: 118 vs. 80 nmol/L; P < 0.10; median enterolactone: 990 vs. 412 nmol/L; P < 0.05) and were associated with significantly shorter TTP in models based on both individual and couples' concentrations (couples' models: enterodiol FOR, 1.13; 95% CI: 1.02, 1.26; enterolactone FOR, 1.11; 95% CI: 1.01, 1.21). Male lignan concentrations were not associated with TTP, nor were isoflavone concentrations. Sensitivity analyses showed that associations observed are unlikely to be explained by potential unmeasured confounding by lifestyle or other nutrients. Our results suggest that female urinary lignan concentrations at levels characteristic of the U.S. population are associated with a shorter TTP among couples who are attempting to conceive, highlighting the importance of dietary influences on fecundity.

Female dietary antioxidant intake and time to pregnancy among couples treated for unexplained infertility.

OBJECTIVE: To determine whether increased antioxidant intake in women is associated with shorter time to pregnancy (TTP) among a cohort of couples being treated for unexplained infertility. DESIGN: Secondary data analysis of a randomized controlled trial. SETTING: Academic medical center associated with a private infertility center. PATIENTS: Females with unexplained infertility. INTERVENTIONS: None. MAIN OUTCOME MEASURE(S): The time it took to establish a pregnancy that led to a live birth. RESULT(S): Mean nutrient intake exceeded the estimated average requirement (EAR) for vitamins C and E. No differences in mean intake of any of the antioxidants were noted between women who delivered a live-born infant during the study period vs. those who did not. In multivariable models, intake of ß-carotene from dietary supplements was associated with shorter TTP among women with body mass index (BMI) ≥25 kg/m(2) (hazard ratio [HR] 1.29, 95% confidence interval [CI] 1.09-1.53) and women <35 y (HR 1.19, 95% CI 1.01-1.41). Intake of vitamin C from dietary supplements was associated with shorter TTP among women with BMI <25 kg/m(2) (HR 1.09, 95% CI 1.03-1.15) and women <35 y (HR 1.10, 95% CI 1.02-1.18). Intake of vitamin E from dietary supplements among women ≥35 y also was associated with shorter TTP (HR 1.07, 95% CI 1.01-1.13). CONCLUSION(S): Shorter TTP was observed among women with BMI <25 kg/m(2) with increasing vitamin C, women with BMI ≥25 kg/m(2) with increasing ß-carotene, women <35 y with increasing ß-carotene and vitamin C, and women ≥35 y with increasing vitamin E. CLINICAL TRIAL REGISTRATION NUMBER: NCT00260091.