April 1 (UPI) -- Exposure to chemicals commonly found in plastic and personal care products during pregnancy may contribute to postpartum depression, a study published Thursday by the Journal of Clinical Endocrinology and Metabolism found.
Urine samples collected from 139 pregnant women included in the study showed high levels of bisphenols and phthalates, the researchers said.
Bisphenols are a type of plastic found in many food and beverage containers, while phthalates are a group of chemicals used in detergents, lubricating oils, food packaging and products such as cosmetics and hair products, according to the U.S. Food and Drug Administration.
The presence of these chemicals in women's bodies during pregnancy was found to lower progesterone levels in their blood by an average of 8% and increase their risk for postpartum depression by nearly 50%, the data showed.
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"We found that phthalate exposure was associated with lower progesterone levels during pregnancy and a greater likelihood of developing postpartum depression," study co-author Melanie Jacobson 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," said Jacobson, an epidemiologist at New York University Langone Medical Center in New York City.
Postpartum depression is a common psychiatric disorder that affects up to one in five childbearing women, according to the U.S. Centers for Disease Control and Prevention.
The cause of the disorder remains unknown, but hormonal changes during pregnancy have been found to be an important factor, Jacobson and her colleagues said.
Chemicals such as bisphenols and phthalates are known to affect sex hormones and may cause hormonal shifts during pregnancy, the Endocrine Society said.
For this study, the researchers measured the levels of bisphenols and phthalates in urine samples and sex hormones in blood samples from 139 pregnant women.
They assessed the women for postpartum depression four months after childbirth using the Edinburgh Postnatal Depression Scale, a commonly used diagnostic tool.
Women with higher levels of phthalates in their urine were 48% more likely to develop postpartum depression.
The women also had lower levels of progesterone, a hormone that plays an important role in the menstrual cycle and in modulating mood, the researchers said.
"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," Jacobson said.
However, "these results need to be interpreted with caution as this is the first study to examine these chemicals in relation to postpartum depression and our sample size was small," she said.
