Phthalates are everywhere — you can find these chemicals in plastic food and beverage containers, laundry detergent, deodorant, shampoo, perfume, insect repellent, carpeting, shower curtains, and plastic toys, to name just a few items. Now, new research from the University of Pittsburgh Graduate School of Public Health explains exactly how harmful these chemicals may be to pregnant women. Exposure to phthalates early in pregnancy disrupts a pregnancy hormone which, in turn, negatively impacts the masculinization of male babies’ genitals, the researchers believe.

For the study, Dr. Jennifer Adibi, assistant professor of epidemiology at Pitt Public Health, and her colleagues analyzed data gathered from 350 women and their babies. All of the participants had enrolled at prenatal clinics in California, Washington, Minnesota and New York. Between 2010 and 2012, the women gave blood and urine samples during their first trimester of pregnancy as part of the The Infant Development and the Environment Study. Months later, they allowed researchers to take measurements of their babies.

In particular, the team of researchers focused on a pregnancy hormone called human chorionic gonadotropin (hCG), which is made by the placenta. Indirectly, this hormone helps sustain and protect the growing fetus in a mother’s womb and can be measured in the mother's blood and urine.

The first tests conducted by the researchers looked at the relationship between hCG and traces of phthalates, tracked through two molecules produced when phthalates are digested — mono-n-butyl and monobenzyl phthalate. These molecules (found in a mother’s urine during early pregnancy) linked to lower levels of hCG in those women carrying male babies and higher levels of hCG in those women carrying female babies.

In a second test, the researchers looked at hCG levels in relation to anogenital distance, which is the span between the anus and genitals. In men, a short anogenital distance often signifies a decreased sperm count and infertility. Here, they discovered a link between phthalate exposure and a shorter anogenital distance in male babies. About 20 to 30 percent of the phthalate effect on the babies' genitals, the researchers estimated, could be attributed to the influence of phthalates on hCG, specifically mono-n-butyl and mono-ethylhexyl phthalate.

"Phthalates are pervasive," Adibi stated at the Endocrinology annual meeting where she unveiled her new research. "Reducing exposure to phthalates and other hormone-disrupting chemicals is something that needs to be addressed at a societal level through consumer advocacy and regulation, and education of health care providers."

Source: Adibi J, et al. Endocrine Society's 97th annual meeting. 2015.