Exposure to Endocrine-Disrupting Chemicals Increases Risk of Post-Partum Depression

While the causes of postpartum depression (PPD) remain poorly understood, perinatal sex hormone fluctuations remain an important factor for future research.

In particular, allopregnanolone has emerged in recent years as a key factor that warrants more studies.

Unlike synthetic environmental chemicals commonly found in plastics and personal care products like bisphenols and phthalates, which are known to impact sex hormones, researchers have not examined allopregnanolone and whether or not these hormonal changes can directly lead to post-partum depression.

A team, led by Melanie H. Jacobson, PhD, MPH, Department of Pediatrics, Division of Environmental Pediatrics, NYU Langone Medical Center, investigated the associations of repeated measures of urinary bisphenols and phthalates in early- and mid-pregnancy with serum pregnenolone, progesterone, allopregnanolone, and pregnanolone concentrations in mid-pregnancy and PPD symptoms at 4 months postpartum.

The Cohort

In the prospective cohort study, the researchers examined 139 pregnant women between 2016-2018.

The investigators measured bisphenols and phthalates in early- and mid-pregnancy urine samples and measured serum sex steroid hormone concentrations in mid-pregnancy. They also assessed post-partum depression at 4 months using the Edinburgh Postnatal Depression Scale (EPDS).

Ultimately, multiple informant models were fit using generalized estimating equations.

The researchers sought main outcomes of serum levels of allopregnanolone, progesterone, pregnanolone, and pregnenolone, examined as continuous EPDS scores and dichotomously with scores of at least 10 defined as post-partum depression.

The Results

“Di-n-octyl phthalate (DnOP) and diisononyl phthalate (DiNP) metabolites were associated with reduced progesterone concentrations,” the authors wrote. “Log-unit increases in ∑DnOP and ∑DiNP predicted 8.1% (95% CI, -15.2% to -0.4%) and 7.7% (95% CI, -13.3% to -1.7%) lower progesterone, respectively. ∑DnOP was associated with increased odds of PPD (odds ratio, 1.48; 95% CI 1.04-2.11)).

Overall, the results show this association warrants future research.

“Endocrine disrupting chemicals may influence hormonal shifts during pregnancy as well as contribute to PPD,” the authors wrote.

About 20% of childbearing women in the US suffer from postpartum depression.

Endocrine-Disrupting Chemicals

Endocrine-disrupting chemicals are widely used in consumer products such as food processing and packaging equipment, personal care products, and pharmaceuticals.

In 2020, researchers found endocrine-disrupting chemical exposure could substantially increase the risk of developing ADHD.

A US research team, led by Jessica R. Shoaff, PhD, Channing Division of Network Medicine, Harvard Medical School, Brigham and Women’s Hospital, evaluated the link between exposure to select endocrine-disrupting chemicals during adolescence and ADHD-related behaviors.

Currently, ADHD is the most common childhood neurobehavioral disorder, impacting approximately 9.4% of children in the US. It is believed that prenatal and early childhood exposure to endocrine-disrupting chemicals could be linked to ADHD, but it has not been examined during adolescence.

The researchers found 82 scores (40%) consistent with a significant behavioral issue, 39 (19%) of which had an ADHD diagnosis. For each two-fold increase in the sum of antiandrogenic phthalate concentration there was a 1.34 (95% CI, 1.00-1.79) increase in the risk of significant ADHD-related behavior problem.

The study, “Prenatal exposure to bisphenols and phthalates and postpartum depression: The role of neurosteroid hormone disruption,” was published online in The Journal of Clinical Endocrinology & Metabolism.