Babies born to women who smoke during pregnancy are at an increased risk of developing a number of different infections, which could lead to hospitalisation or even death, a new study indicates.

Researchers analysed the hospitalisation records and death certificates of 50,000 babies born in an area of the US between 1987 and 2004. Both respiratory and non-respiratory infections were taken into account.

The study found that the babies of mothers who smoked during pregnancy were 50% more likely to be hospitalised or to die from a range of infections, compared to babies whose mothers did not smoke.

According to the researchers, it has long been known that the babies of smokers are at an increased risk of medical problems relating to premature delivery, poor lung development and low birth weight.

"However, while respiratory infections have been recognised as a common cause of these sometimes life-threatening illnesses, this study shows that babies exposed to smoke in utero also have increased risk for hospitalisation and death from a much broader range of infections - both respiratory and non-respiratory - than we knew before," explained Dr Abigail Halperin of the University of Washington.

The results stood even if the baby was born at full-term and had a normal weight - they were still at an increased risk of hospitalisation or death if their mother smoked.

The findings suggest that the immune systems of babies who are exposed to smoke while still in the womb are compromised ‘more generally, not just within the respiratory system'.

However, the study also found that if pregnant women quit smoking or cut down during their pregnancy, the child's risk of infection appeared to decrease.

"Counseling pregnant women to reduce their smoking, if they are not able to quit completely, may help reduce infant hospitalisations or death," Dr Halperin said.

Details of these findings were published in the journal, Pediatric Infectious Diseases and are due to be presented at the American Academy of Pediatrics (AAP) National Conference and Exhibition in Orlando this weekend.

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