Health Topics

Smoking and the risk of gestational diabetes: another reason to quit smoking

Tobacco is associated with both an increase in the risk of developing type 2 diabetes and there is a clear relationship between smoking during pregnancy and low-birth-weight infants and premature births. So what are the consequences for expectant mothers who smoke before and during pregnancy?

Adults who smoke have a greater risk of developing type 2 diabetes (T2D), probably due to the oxidative stress and inflammation caused by smoking. The presence of other types of diabetes, such as gestational diabetes (GD), also increases both the mother’s and child’s risk of developing type 2 diabetes in the future.

Gestational diabetes is fairly common (it affects 9% of pregnancies in Spain) and the classic risk factors for its appearance are being overweight, an advanced maternal age, a history of GD in previous pregnancies and relatives with diabetes. However, to date there is still no conclusive information regarding the risk of developing gestational diabetes with respect to tobacco use. In this context, a recent study by the University of Jerusalem has presented some very revealing information. The authors analysed a US database used to monitor the risk involved with pregnancy (Pregnancy Risk Assessment Monitoring System).

They evaluated data collected from 222,408 pregnancies between 2009 and 2015, focusing on tobacco consumption during pregnancy and mothers who had GD. The study included nonsmokers, women who quit because they were pregnant, others who reduced the amount they smoked and those who smoked the same or even more cigarettes during pregnancy. Out of all the pregnancies, 5.3% coursed with gestational diabetes.

Expectant mothers who smoked the same or more than usual during pregnancy had a 46% higher risk of developing gestational diabetes than nonsmoker. Women who managed to reduce the amount they smoked during pregnancy faced a 22% greater risk. This increased risk of GD did not present any correlation with the subjects’ pre-pregnancy body mass index (BMI) or weight gain during gestation.

Gestational diabetes can lead to medical problems for both the mother and newborn. The main short-term issue is weight gain, while in the mid- to long-term there is an increased chance of T2D. So this study has shown that tobacco is also a risk factor for the onset of GD, which was a little known fact until its publication. Smoking before falling pregnant clearly increases the risk, so this is a very important point to consider for women who are trying to conceive. Furthermore, the risk of GD is lower in women who, although they continue smoking, at least smoke fewer cigarettes. These are further reasons why expectant mothers should stop smoking tobacco during pregnancy, besides the previously confirmed risks of premature birth and low birth weights. 

Author: Dr Enric Esmatjes, endocrinologist at the Hospital Clínic

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