Smoking while pregnant increases the risk of gestational diabetes

NEW YORK — A new study has found that women who smoke while pregnant, even if they have cut down the number of cigarettes they smoke each day, could be increasing their risk of developing gestational diabetes mellitus.

Carried out by researchers at the Hebrew University of Jerusalem’s Braun School of Public Health and Community Medicine, Israel, in collaboration with Ohio University, USA, the new study analysed data collected by the United States’ Centres for Disease Control and Prevention (CDC) from 222,408 women, of which 12,897 (5.3 per cent) were diagnosed with gestational diabetes.

The women had been asked to report any changes in smoking status during pregnancy, including whether they were a non-smoker, had quit smoking, had reduced the amount smoked, or if they smoked the same or more, and self-report on whether they had gestational diabetes — a condition that can lead to higher risks for pregnancy and birth complications such as macrosomia (larger than average babies) and caesarean deliveries. 

The findings, published this week in Obstetrics & Gynecology, showed that after taking into account well-known risk factors for gestational diabetes, such as maternal age, pre-pregnancy body mass index and pregnancy weight gain, the pregnant women who smoked the same or more cigarettes per day as they did before becoming pregnant were nearly 50 per cent more likely to develop gestational diabetes. 

Reducing the amount of cigarettes smoked each day did reduce the risk, but even women who cut down still had a 22 per cent higher risk of gestational diabetes than women who never smoked or who quit smoking two years before they became pregnant.

“Ideally, women should quit smoking before they try to become pregnant,” said Dr Yael Bar-Zeev. “Further, due to the high risks involved, it’s imperative that pregnant smokers have access to pregnancy-specific smoking cessation programs. Currently, in the United States and Israel, these services are not accessible enough or not tailored for pregnant women and that needs to change.”

The researchers also pointed out that smoking during pregnancy is one of the most significant risk factors for poor pregnancy outcomes, putting babies at a higher risk for premature birth, low birth weight and developmental delays than babies born to non-smoking mothers.