A common genetic variant could make it difficult for pregnant women to quit smoking, say Scientists from Peninsula Medical School and the University of Bristol.
They found that variation in 15q24 nicotinic acetylcholine receptor gene receptor cluster is associated with a reduced ability of women to quit smoking in pregnancy.
For the study, the researchers looked at 7,845 women of European descent from the South West of England.
Using 2,474 women who smoked regularly immediately before they became pregnant, the association between the variant and smoking cessation and smoking quantity during pregnancy was analysed.
When asked about smoking in the first trimester of pregnancy, 28 pct of the women said they had given up.
However, this figure was only 21pct in the group of women with two copies of the smoking addiction gene, whereas in women with two copies of the non-addictive gene, 31pct said they had quit.
In the third trimester, 47pct of women with two copies of the non-addictive gene had stopped smoking, compared with only 34pct of women with two copies of the smoking addiction gene.
"Pregnant women are under considerable health and social pressure to stop smoking, and quitting in such circumstances is influenced by a number of factors including the age of the expectant mother, their education and whether or not their partners smoke," said Dr. Rachel Freathy from the Peninsula Medical School.
"However, we were keen to investigate whether the genetic variant that influences increased cigarette consumption also had a role to play as an extra hurdle to quitting smoking during pregnancy, and our study suggests that it does," she added.
The study is published in Human Molecular Genetics.