Researchers have found that women who smoke during pregnancy can have unhealthy baby as smoking causes DNA change in the baby.

This change is termed as DNA methylation and causes dysfunction of the genes. The researchers claimed that this change in the DNA makes the immune system of the baby weak and makes the baby prone to diseases.

This study has been conducted by the American Thoracic Society in Denver. They have analysed babies of 173 mothers and have discussed about their smoking habits. DNA sample checks of the cheeks and the babies are collected.

The researchers have found that the mothers who smoke during pregnancy did damage to their own babies. They have found that the babies have got DNA methylation which has caused their immune system to degrade.

"Imprinted genes appear to be particularly susceptible to these exposures since they come from one parent and only a single copy from one chromosome in DNA is active", study author Carrie Breton, an assistant professor of preventive medicine at the University of Southern California said in an American Thoracic Society news release.

Health experts always warn pregnant mothers to smoke as this causes harm to their babies. Health officials are organizing different awareness programs to make pregnant mothers aware about the ill effects to smoking.