Smoking during pregnancy increases the risk of your child suffering behavioural problems when they reach preschool, according to a new study.

Previous studies have found that smoking in pregnancy can increase the risk of premature delivery, cot death and stunted growth, but this is the first to link smoking to behavioural problems in young children.

Of 13,000 mums-to-be in the study, 10% reported smoking heavily during their pregnancy (more than 10 cigarettes a day), 13% were light smokers (less than 10 cigarettes a day) and 12% quit smoking during their pregnancy.

Mums were asked questions about their child's behaviour at 3 years old, such as whether their child was argumentative, constantly squirmy, or easily distracted.

Researchers found that heavy smoking, in particular, was linked to significant increased risk of conduct, hyperactivity and inattention problems in boys and conduct problems in girls.

If you want to stub it out, help is at hand.