Ever feel like you’re getting chemical overload? If you want to detox — especially if you’re pregnant — start with your hair. A small step you can take towards toxin-free living is to use shampoo that is “phthalate-free.” Phthalates are chemicals commonly found in plastics and vinyl flooring, and they often lurk in shampoos, hair sprays, perfumes and moisturizers as well.

“Phthalates may cause endocrine [hormone] disturbances and other effects,” says Dr. John Meeker, assistant professor of environmental health sciences at the University of Michigan School of Public Health in Ann Arbor, Mich. “Animal studies and limited human studies have reported adverse effects on reproduction, fetal development and other processes.”

A new study of pregnant women led by Meeker suggests that phthalates may contribute to a growing number of premature births. He and colleagues in the U.S. and Mexico studied data from 60 pregnant women who had been enrolled in a larger study conducted at prenatal clinics in Mexico.

Half of the women carried their babies to term and half of them delivered prematurely. Results showed that women who delivered premature babies had, on average, three times the levels of phthalates in their urine, compared to women who delivered their babies at full-term. Another study — this one in Shanghai -— found that when babies in the womb are exposed to phthalates, they are more likely to have a low birth weight.

Although neither of these studies prove that phthalates cause health problems, they do add to the evidence that phthalate exposure might be a concern in our health and the health of our children.

So what can you do to limit your exposure? Look for products that say “phthalate-free” on the label, Meeker advises. He also suggests there are resources on the web that list phthalate-free products.

Your best bet is to buy fragrance-free shampoos and soaps whenever possible, “although unscented products are not guaranteed to be phthalate free,” says Meeker.