The presence of the chemical compounds di-n-octyl phthalate and diisononyl phthalate in pregnant women was associated with reduced progesterone concentrations mid-pregnancy, and the presence of di-n-octyl phthalate alone was associated with postpartum depression four months after delivery, a new study shows.
Researchers writing in the April 1 online issue of The Journal of Clinical Endocrinology and Metabolism conducted a prospective cohort study between 2016 and 2018 of 139 pregnant women to examine possible associations between exposures to environmental chemicals and postpartum depression. Urine samples were taken to measure bisphenols and phthalates in early and mid-pregnancy. They also measured for fluctuations in sex hormones in mid-pregnancy, however, but no significant association was found between hormones and exposure to bisphenols and phthalates with postpartum depression.
The presence of di-n-octyl phthalate and its association with lower prenatal progesterone and greater postpartum depression was “consistent with the hypothesis that endocrine disrupting chemicals could drive hormonal shifts which could affect postpartum depression. Our observation that di-n-octyl phthalate was associated with postpartum depression suggests that because phthalate exposure can be reduced through dietary and behavioral interventions—such as avoid using food packaging, certain cosmetics, and polycarbonate plastic products—these findings provide preliminary evidence identifying prenatal exposure to phthalates as a potentially modifiable risk factor for postpartum depression.”
Increases in di-n-octyl phthalate (DnOP) and diisononyl phthalate (DiNP) predicted 8.1% (95% CI: -15.2%, -0.4%) and 7.7% (95% CI: -13.3%, -1.7%) lower progesterone, respectively. The increased odds ratio for di-n-octyl phthalate and its link to postpartum depression was 1.48 (95% CI: 1.04, 2.11).
“The results were robust to covariate adjustment and remained consistent after excluding women on psychotropic or progesterone-disrupting medications and implementing an alternate method for urinary creatinine adjustment,” the authors wrote.
Bisphenols are used in polycarbonate plastics and aluminum can lining, and phthalates, are used personal care products. They represent two classes of endocrine disrupting chemicals (EDCs) that are commonplace are detectable in nearly all pregnant women.
The authors highlighted previous studies that showed bisphenol A (BPA), in rat models, was associated with decreased estradiol and progesterone levels and di-2-ethylhexyl phthalate and dibutyl phthalate inhibit the production of estradiol and progesterone in cycling and pregnant rats. Epidemiological studies have linked BPA to lower estradiol among pregnant women and women undergoing in vitro fertilization. Monoethyl phthalate and mono(carboxy-isooctyl) phthalate have been linked to reduced progesterone.
There were several limitations in this study including the small sample size, the lack of psychiatric evaluation or clinical diagnosis, and non-persistent exposures assessed in spot urine samples.
“The results of this study underscore the potential for EDCs to impact hormonally-mediated health outcomes and expand the scope of conditions typically considered susceptible to EDCs. While postpartum depression remains under-diagnosed, under-studied, and with few known modifiable risk factors, work in this avenue seeks to understand whether exposure to synthetic environmental chemicals during pregnancy may play a role,” the authors wrote.
Melanie H Jacobson, PhD, MPH, Cheryl R Stein, PhD, Mengling Liu, PhD, et al. “Prenatal exposure to bisphenols and phthalates and postpartum depression: The role of neurosteroid hormone disruption,” Journal of Clinical Endocrinology and Metabolism. Published April 1, 2021. https://doi.org/10.1210/clinem/dgab199