At 17 weeks of pregnancy, participants in MoBa were asked about their own mother’s smoking habits when they were in the womb. More than 74 000 participants could answer this.

Increased risk of overweight, high blood pressure and gestational diabetes

More than one in four (27.8 per cent) reported that they were indirectly exposed to tobacco through smoking in pregnancy. What significance did this have 20-40 years later, when the daughters began to reproduce? 

• The risk of overweight was increased by 53 per cent 
• The risk of high blood pressure was increased by 68 per cent 
• The risk of gestational diabetes was increased by 32 per cent

Lifestyle factors often repeat over generations; for example, smoking was more common among those who were exposed to smoking before birth, so all the calculations were adjusted for possible reconstituted effects. Overweight increases the risk of both high blood pressure and gestational diabetes. However, even after correction for overweight, the risk of high blood pressure and gestational diabetes increased in women who had been exposed to smoking before birth.

In the mid-80s more than a third of pregnant women smoked. The proportion of daily adult smokers in Norway has decreased from 30 to 17 per cent in the last decade. In 2009, it was reported that 16.4 per cent of pregnant women smoked at the start of pregnancy, while 7.2 per cent smoked in late pregnancy.

The study was a collaboration between the Norwegian Institute of Public Health Institute and the National Institute of Health Sciences in the USA.

Reference

Environmental Health Perspectives: In Utero Exposure to Maternal Tobacco Smoke and Subsequent Obesity, Hypertension, and Gestational Diabetes Among Women in The MoBa Cohort. Lea A. Cupul-Uicab, Rolv Skjærven, Kjell Haug, Kari K. Melve, Stephanie M. Engel, Matthew P. Longnecker.