Pregnant women who are exposed to chemicals in nail polish, shampoo, and toys may have a higher postpartum depression risk

• Exposure to common chemicals in pregnancy is linked to postpartum depression (PPD), a study found.
• The chemicals, found in plastics and beauty products, seem to lower progesterone, which affects PPD.
• While not completely avoidable, limiting chemical exposure may be one way to reduce PPD risk.

The more pregnant people are exposed to common endocrine-disrupting chemicals, the more likely they are to develop postpartum depression, a small study in the Endocrine Society's Journal of Clinical Endocrinology & Metabolism found.

The chemicals, called phthalates, make plastic more flexible and prolong fragrances' shelf life. They're found in beauty products like nail polish, aftershave, shampoo, and perfume, as well as toys, PVC pipes, and vinyl flooring.

While the study was small and could not prove cause and effect, it makes sense that such chemicals, which are known to affect hormones, could play a role in postpartum depression (PPD), which is also influenced by hormonal changes after birth.

"This research is important because phthalates are so prevalent in the environment that they are detectable in nearly all pregnant women in the United States," study author Melanie Jacobson of the NYU Langone Medical Center in New York said in a press release.

"If these chemicals can affect prenatal hormone levels and subsequently postpartum depression, reducing exposure to these types of chemicals could be a plausible avenue for preventing postpartum depression."

The study is the first to look specifically at how phthalates' effect on hormones could influence postpartum depression risk

To conduct the study, researchers followed 139 women throughout their pregnancies and four months postpartum. Most identified as Hispanic and had only completed high school or some college.

During pregnancy, the participants filled out questionnaires detailing factors like their medical history, health behaviors, and depressive symptoms.

The researchers also took the women's urine and blood samples to measure their levels of bisphenols (another type of endocrine-disrupting chemical found in plastics) and phthalates, as well as their sex hormones.

Then, four months after their deliveries, the researchers assessed the participants for PPD, while also taking into account issues like their social conditions, birth outcomes, and antidepressant use.

The study authors found that women with higher levels of phthalates in their urine were more likely to meet criteria for PPD. Still, only 12 of the 139 women studied, or less than 9%, met criteria for diagnosable postpartum depression, while estimates of its prevalence nationally range from 10% to 25%. Those with PPD tended to be older, single, and experienced depressive symptoms during pregnancy.

Importantly, the researchers also found that the higher chemical exposure was also linked to lower levels of progesterone, which affects menstruation and modulates mood. This "robust" finding aligns with the hypothesis that endocrine-disrupting chemicals drive hormonal shifts, which can affect PPD, the study authors wrote.

However, other factors could be at play and more research is needed. The study is the first to look specifically at how chemicals' effects on hormones could affect PPD risk, though past research has shown that endocrine-disrupting hormones are linked to adverse birth outcomes, like preterm birth.

The researchers say avoiding food packaging and certain cosmetics and plastics during pregnancy could be an easier way to reduce postpartum depression risk than changing your genetic predisposition or socioeconomic status, which both also affect how prone your are to the condition.