SMOKERS who quit when they get pregnant can still harm their child, a study shows.
The damage may already have been done by the time they conceive.
Babies in the womb were nearly a day behind in women who smoked ten or more cigarettes a day, researchers found.
Smoking before and after pregnancy led to smaller foetuses at 20 weeks and smaller babies, the study in Rotterdam, the Netherlands, shows.
Researcher Dr Melek Rousian said: “The results of this study emphasise the importance of smoking cessation prior to conception and that efforts to help women stop smoking should focus on this time window.
“If possible, women should stop smoking from the very moment they plan to become pregnant, but it’s always a good thing to stop smoking anyway, particularly at any stage of pregnancy.
“Smoking not only impacts an embryo’s growth during pregnancy and birth weight, but also embryo development right from the very early stages of pregnancy.”
The researchers are now exploring different ways of helping future parents stop smoking through face-to-face consultations, follow-up visits and digital interventions.
Dr Rousian added: “This is why the periconceptional period is an important area of research because many future parents are not aware of the presence of a developing embryo in the early days when a pregnancy has not yet been confirmed.”