Researchers said that although the link was "relatively modest", even limited hearing loss can have implications for kids' learning and social skills -- so it's important to reach out to those who might need help, and to prevent as much exposure as possible.
"The findings should be part of all our efforts to get people not to smoke, and especially not to smoke when they're pregnant," said Dr Michael Weitzman, a child health researcher from the New York University School of Medicine, who led the study.
Range of problems
Past research has tied smoking during pregnancy to a range of childhood problems, including asthma and learning disabilities. In another study, Weitzman and his colleagues found exposure to second hand smoke during adolescence was linked to hearing loss, based on blood tests for nicotine-related products.
This time they analysed data on a group of 12- to 15-year-olds who underwent hearing tests in 2005-2006 as part of a national health survey, and whose parents were asked about smoking during pregnancy. The hearing exams were done in both ears to see if kids had any trouble picking up sounds at different pitches.
Just over 16% of youths had moms who smoked while pregnant, the study team reported in JAMA Otolaryngology -- Head & Neck Surgery. Those kids were especially at risk for hearing loss at the lower frequencies of human speech: one in six had hearing problems in one ear, compared to one in 14 whose moms didn't smoke. Weitzman said many teens with mild hearing loss don't realise they have a problem, but that it can lead to irritability and trouble in school.
Reduced oxygen flow
What's more, he told Reuters Health, it's possible the mild hearing loss measured in some adolescents will only get worse in adulthood. Hearing researcher Abbey Berg from Pace University in New York said the findings "make sense", given what is known about risks to the baby when a woman smokes during pregnancy, including reduced oxygen flow.
"There are also toxins in the cigarettes, as well that we don't even know necessarily what those are and what the effects of those are," said Dr Josef Shargorodsky, from Massachusetts Eye and Ear Infirmary and Brigham and Women's Hospital in Boston."There are so many other risks of smoking in pregnancy," Shargorodsky, who wasn't involved in the research, told Reuters Health. "Preventing exposures is the most important thing."
"Berg, who also didn't participate in the new study, said children who have been exposed can be counselled growing up about how to prevent further damage to their hearing."These kids could be monitored and hearing conservation and hearing education could be started at a very young age," she told Reuters Health. Weitzman agreed that it's important to spot young people with hearing trouble early."Parents might really want to consider having their 12- to 15-year-olds undergo hearing tests if they smoked during pregnancy," he said.