Smoking isn’t only bad for your health, but may also affect your baby, according to a new study.

The study, conducted by scientists from the University of Leicester Medical School and in collaboration with Warwick University, concluded that children who have at least one parent who smokes have 5.5 times higher levels of cotinine in urine. Cotinine is a chemical released when the body breaks down nicotine.

The children who have a mother that smokes are the most affected. The cotinine level in their blood is four times higher compared to those who have non-smoking parents.

According to the researchers having a smoking father is also bad for babies. The analyzed samples of urine revealed that those babies have a double amount of cotinine.

"Our findings clearly show that by accumulating cotinine, babies become heavy passive smokers secondary to the active smoking of parents," write the researchers.

Also the study showed that sleeping with parents and lower temperature rooms were also associated with increased amounts of cotinine.

The authors say: ‘Babies affected by smoke tend to come from poorer homes, which may have smaller rooms and inadequate heating.

‘Higher cotinine levels in colder times of year may be a reflection of the other key factors which influence exposure to passive smoking, such as poorer ventilation or a greater tendency for parents to smoke indoors in winter.’

Similar to other European countries, UK will adopt soon a legislation to ban smoking in public places.