Urinary bisphenol A concentrations and association with in vitro fertilization outcomes among women from a fertility clinic.
Level 3 - non-randomized controlled study
Prospective cohort study examining an environmental exposure and reproductive outcomes.
PubMed 26209788 · doi:10.1093/humrep/dev183
What was done
Researchers prospectively evaluated 256 women undergoing 375 in vitro fertilization (IVF) cycles between 2004 and 2012 at the Massachusetts General Hospital Fertility Center (part of the EARTH Study). Participants provided up to two urine samples prior to oocyte retrieval (total N = 673). Generalized linear mixed models with random intercepts assessed associations between specific gravity-adjusted urinary bisphenol A (BPA) concentrations and both intermediate and clinical IVF outcomes, adjusting for age, race, body mass index, smoking status, and infertility diagnosis.
What was found
The specific gravity-adjusted geometric mean urinary BPA was 1.87 µg/l. Urinary BPA concentrations were not associated with endometrial wall thickness, peak estradiol levels, proportion of high-quality embryos, or fertilization rates. BPA levels were also not associated with implantation, clinical pregnancy, or live birth rates per initiated cycle or per embryo transfer. Age modified the relationship with endometrial thickness: younger women (<37 years) had thicker endometrium across increasing BPA quartiles, whereas older women (≥37 years) had thinner endometrium.
Why it matters
Despite animal evidence suggesting BPA disrupts ovarian and uterine function, typical human exposure levels were not associated with adverse reproductive or live birth outcomes in women undergoing assisted reproduction.
Limits
The study is subject to potential exposure misclassification due to the short biological half-life of BPA measured in spot urine samples. Findings from a subfertile clinic population may not generalize to natural conception in the broader population.
Cited by
- contradicts The EARTH study demonstrated that higher exposure to endocrine-disrupting chemicals is associated with increased time to pregnancy and worse IVF outcomes, including fewer retrieved eggs, fewer embryos, and poorer sperm counts.