Smoking during pregnancy increases the risk of the child developing diabetes and obesity in later life, find researchers from Sweden in this week’s BMJ. They also show that cigarette smoking as a young adult is associated with an increased risk of subsequent diabetes.
The authors used British data on about 17,000 births from 3 to 9 March 1958 to conduct their study. At birth, midwives recorded information on smoking during pregnancy (after the 4th month). Details of maternal smoking were again recorded in 1974. The group’s own smoking behaviour was recorded during an interview at age 16.
Medical examinations and record reviews were conducted at ages 7 and 16 years, and a personal interview at age 33 years asked about diabetes. Among those followed fully throughout childhood and adolescence to age 33, the authors identified 15 men and 13 women who had developed diabetes between 16 and 33 years, and 602 individuals (10%) who were obese at age 33.
The association of diabetes with maternal smoking specifically during pregnancy suggests that it is a true risk factor for early adult onset diabetes, say the authors. Cigarette smoking as a young adult was also independently associated with an increased risk of subsequent diabetes. Study members without diabetes, but whose mothers smoked during pregnancy, were significantly more likely to be obese or overweight by age 33 years.
They suggest that in utero exposure to smoking results in lifelong metabolic dysregulation, possibly due to fetal malnutrition or toxicity, and stress that smoking during pregnancy should always be strongly discouraged.