Study: Quit smoking before 15th week of pregnancy, reduce risk of premature birth

LONDON Pregnant women who quit smoking before the 15th week of pregnancy reduce their risk of premature birth and having small babies as compared with women who don’t smoke, a new study published in the British Medical Association journal BMJ reported last week.

Women who didn’t quit smoking by 15 weeks were three times more likely to give birth prematurely and twice as likely to have smaller babies, compared to women who stopped smoking, reported lead researcher Lesley McCowan.

Smoking during pregnancy increases the risk of miscarriage, ectopic pregnancy, premature birth, small babies, stillbirth and neonatal death, but no study had determined whether stopping smoking in early pregnancy reduced the risks of small babies and premature births, the study authors said.

For the study, McCowan's team collected data on 2,504 pregnant women — including 80% who did not smoke, 10% had smoked in the past but had quit and 10% who were current smokers.

There was no difference in the rate of spontaneous premature birth or smaller babies between women who did not smoke and those who had stopped by week 15, the researchers found. However, women who continued to smoke had higher rates of spontaneous preterm birth than woman who quit (10% vs. 4%) and higher rates of smaller babies (17% vs. 10%).

“Maternity care providers should strive to assist pregnant women who smoke to stop early in pregnancy, emphasising the major health benefits if they cease to smoke before 15 weeks’ gestation,” McCowan concluded.