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Smoking during pregnancy is one of the most significant risk factors for poor pregnancy outcomes. In the United States, 10.7 percent of all women smoke during their pregnancy or are exposed to secondhand smoke. Consequently, their babies are at a higher risk for premature birth, low birth weight and developmental delays than those of their non-smoking counterparts.

In addition to these risks, an international research team headed by Dr. Yael Bar-Zeev at the Hebrew University of Jerusalem's Braun School of Public Health and Community Medicine, in collaboration with Dr. Haile Zelalem and Professor Ilana Chertok at Ohio University, found that smoking during pregnancy may also increase a woman's risk of developing gestational diabetes mellitus (GDM). Gestational diabetes leads to higher risks for pregnancy and birth complications such as macrosomia (larger than average babies) and caesarean deliveries. The findings were published this week in Obstetrics & Gynecology.

Bar-Zeev and her team conducted a secondary analysis of data collected by the United States' Centers for Disease Control and Prevention (CDC) called the Pregnancy Risk Assessment Monitoring System (PRAMS). For this study, they looked at 222,408 women who gave birth during 2009-2015, of which 12,897 (5.3 percent) were diagnosed with gestational diabetes.

The researchers found that pregnant women who smoke the same or more cigarettes per day as they did before their pregnancy are nearly 50 percent more likely to develop gestational diabetes. Those pregnant women who cut down on their number of cigarettes have a 22 percent higher risk 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," Bar-Zeev cautioned. "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 , and that needs to change."

More information: Yael Bar-Zeev et al, Association Between Prenatal Smoking and Gestational Diabetes Mellitus, Obstetrics & Gynecology (2019). dx.doi.org/10.1097/AOG.0000000000003602

Journal information: Obstetrics & Gynecology