Tokyo, Jun 6 (IANS): If you are planning to start motherhood, quit smoking, say researchers. Exposing your baby to tobacco smoke during pregnancy or after the birth may cause hearing impairment in them.

According to the researchers, babies who were exposed to smoking during pregnancy had a 68 per cent increased relative risk of developing hearing problems.

"This study clearly shows that preventing exposure to tobacco smoke during pregnancy and postnatally may reduce the risk of hearing problems in children," said Koji Kawakami from the Kyoto University in Japan.

The study, published in the journal Pediatric and Perinatal Epidemiology, included data from 50,734 children aged 3 years.

Out of the group, 3.8 per cent were exposed to smoking only during pregnancy, 3.9 per cent were exposed only to second-hand smoke at 4 months and 0.9 per cent were exposed to tobacco smoke during pregnancy and at 4 months.

The results showed that the prevalence of hearing impairment among babies aged three who were exposed to smoke was 4.6 per cent while those exposed to only second-hand smoke at 4 months had a 30 per cent increased relative risk.

Children who were exposed to tobacco smoke during pregnancy and second-hand smoke at 4 months had a 2.4 times increased relative risk.

"The findings remind us of the need to continue strengthening interventions to prevent smoking before and during pregnancy and exposure to second-hand smoke in children," Kawakami added.