Pregnant women who are exposed to hairspray are more likely to have a baby with genital birth defects, a new study suggests. The babies of hairdressers and beauticians were more than twice as likely to be born with hypospadias, a genital defect in which the urinary opening appears on the underside of the penis.

The study included 471 mothers who gave birth to babies with the defect and 490 mothers of children who were not born with the disorder. About twice as many women in the first group said they had been exposed to hairspray through their jobs as hairdressers and beauty therapists. The researchers suggest a group of chemicals called phthalates that are found within hairspray may be to blame. The study was led by researchers from Imperial College London, University College Cork, and the Center for Research in Environmental Epidemiology in Barcelona.

However, women shouldn’t be alarmed, says study leader Professor Paul Elliott. “This study adds a bit more evidence to the general picture about these chemicals, but more research will be needed to demonstrate that the link exists. Pregnant women will need to make their own choices about whether or not to avoid these kinds of exposures.”

The study was published in the journal Environmental Health Perspectives.

Hypospadias are among the most common birth defects of the male genitalia; the suspected environmental agents that may be associated with the disorder include various chemicals, sometimes termed endocrine disruptors, that interact with steroid receptors. A recent study has linked hypospadias with vegetarian diet during pregnancy.