Teens may be at increased risk of hearing loss if their mother smoked during pregnancy, suggests new research.

The study of 964 teens ages 12 to 15 found that 16 percent had been exposed to tobacco smoke prenatally. These teens were almost three times as likely as those not exposed to smoke prenatally to have one-sided, low-frequency hearing loss, HealthDay reports.

Lead researcher Dr. Michael Weitzman of the NYU School of Medicine said prenatal smoke exposure led to an average of less than three decibels of hearing impairment, which he called relatively modest. “[However], an almost three-fold increased odds of unilateral hearing loss in adolescents with prenatal smoke exposure is worrisome,” he wrote in JAMA Otolaryngology—Head and Neck Surgery.

A study published in 2011 suggested exposure to secondhand smoke can lead to hearing loss in teenagers, who often don’t realize they have hearing difficulties. The study found that teens exposed to secondhand smoke were more likely to have both low- and high-frequency hearing loss, compared with teens who were not exposed. The more exposure they had, the more severe their hearing loss. Yet more than 80 percent of those who had hearing loss did not realize it.