Paraben exposure and couple fecundity: a preconception cohort study

Abstract

AbstractSTUDY QUESTIONIs pre-conception exposure to parabens associated with fecundity in couples of childbearing age?SUMMARY ANSWERParaben exposure in female partners was associated with reduced couple fecundity and anti-Müllerian hormone (AMH) might be one of the possible mediators.WHAT IS KNOWN ALREADYThe reproductive toxicity of parabens, a class of widely used preservatives, has been suggested but evidence regarding their effects on couple fecundity is scarce.STUDY DESIGN, SIZE, DURATIONIn this couple-based prospective cohort study, a total of 884 pre-conception couples who participated in the Shanghai Birth Cohort between 2013 and 2015 were included.PARTICIPANTS/MATERIALS, SETTING, METHODSConcentrations of six parabens were measured in urine samples collected from couples. Malondialdehyde, C-reactive protein, and AMH were assessed in female partners. The outcomes included couple fecundability (time-to-pregnancy, TTP) and infertility (TTP > 12 menstrual cycles). Partner-specific and couple-based models were applied to estimate the associations. The joint effect of paraben mixture on couple fecundity was estimated by quantile-based g-computation (q-gcomp). Mediation analysis was used to assess the mediating roles of oxidative stress, inflammation and ovarian reserve.MAIN RESULTS AND THE ROLE OF CHANCEA total of 525 couples (59.4%) conceived spontaneously. In the partner-specific model, propyl paraben (PrP), butyl paraben (BuP), and heptyl paraben (HeP) in female partners were associated with reduced fecundability (fecundability odds ratio (95% CI): 0.96 (0.94–0.98) for PrP; 0.90 (0.87–0.94) for BuP; 0.42 (0.28–0.65) for HeP) and increased risk of infertility (rate ratio (95% CI): 1.06 (1.03–1.10) for PrP; 1.14 (1.08–1.21) for BuP; 1.89 (1.26–2.83) for HeP). Similar associations were observed in the couple-based model. AMH played a significant mediation role in the association (average causal mediation effect (95% CI): 0.001 (0.0001–0.003)). Paraben exposure in male partners was not associated with couple fecundity. The joint effect of paraben mixture on couple fecundity was non-significant.LIMITATIONS, REASONS FOR CAUTIONSelf-reported pregnancy and single urine sample may lead to misclassification. The mediation analysis is limited in that levels of sex hormones were not measured. The inclusion of women with irregular menstrual cycles might affect the results. It is possible that the observed association was due to reverse causation.WIDER IMPLICATIONS OF THE FINDINGSThis is the first study to assess the effects of paraben exposure on couple fecundity in Asians. Given the widespread exposure to parabens in couples of childbearing age, the present findings may have important public health implications.STUDY FUNDING/COMPETING INTEREST(S)This study was supported in part by the National Natural Science Foundation of China (41991314), the Shanghai Science and Technology Development Foundation (22YF1426700), the Science and Technology Commission of Shanghai Municipality (21410713500), and the Shanghai Municipal Health Commission (2020CXJQ01). All authors declare no conflict of interest.TRIAL REGISTRATION NUMBERN/A.