Babies with parents who smoke have cotinine in their urine

British scientists say babies with parents who smoke have five times as much cotinine, a nicotine byproduct, in their urine than infants whose parents are non-smokers.

Parental smoking is known to be a leading risk factor for sudden infant death syndrome.

The study by researchers from the University of Leicester analyzed the urine samples of 104 infants, 71 of whom had parents who smoked.

They found that if a parent of an infant was a smoker, then the amount of cotinine in the urine samples increased by at least two times; if the mother was a smoker, then the cotinine levels rose by 4 times.

The researchers say cotinine levels increased even further if the babies slept with the parents or were in lower temperature rooms.

Dr. Mike Wailoo and his colleagues say the findings clearly indicate that by accumulating cotinine, babies become heavy passive smokers secondary to the active smoking of parents.

Dr. Wailoo says this is the first direct information on the effect of smoking in homes on babies and it clarifies that cotinine is just one of thousands of potentially harmful nicotine byproducts that can accumulate in infants' bodies.

The researchers suggest that most of the babies affected by smoking come from poorer homes which may have smaller rooms and inadequate heating and higher cotinine levels in the colder seasons may be a reflection of other factors such as poorer ventilation or a greater tendency for parents to smoke indoors in winter.

Over 6,000 children under the age of five die each year in the United States alone and the researchers say legislation to prevent smoking in the presence of babies is impractical and cannot be monitored, but educating the parents about the effects of second hand smoking on their babies can be done.

The study is published in the journal, Archives of Disease in Childhood.