While the relationship between tobacco exposure in the womb and negative outcomes in childhood has been much studied, reports on possible adverse effects that persist until adulthood are more scarce and results are inconsistent.  

The study by Dr Kristina Mattsson from Lund University in Sweden and colleagues used data from the Swedish Medical Birth Register. The researchers investigated the relationship between a woman smoking in pregnancy and the chances of her daughter then developing gestational diabetes and obesity.

Data was retrieved for women who were born in 1982 (when smoking data were first registered) or later and who had given birth to at least one child, and 80 189 pregnancies were included.

The data on maternal smoking behaviour in the register is categorised into three categories: non-smokers, moderate smokers (1’€“9 cigarettes/day) and heavy smokers (>9 cigarettes/day).

Among the daughters studied, 7 300 subsequently became obese and 291 developed gestational diabetes when they themselves were pregnant.

The risk of gestational diabetes was increased by 62 percent among women who were moderately exposed to smoking in the womb and 52 percent among those heavily exposed.

The women moderately exposed were 36 percent more likely to be obese and those heavily exposed 58 percent more likely to be obese.

The associations remained after adjustment for age, parity, BMI, mode of delivery, gestational age and birthweight.

The authors suggest possible mechanisms behind the associations could be alterations in the regulation of appetite and satiety, which has been found in animal studies.

Other reported effects of prenatal nicotine exposure include a higher rate of death of the insulin-producing beta cells in the pancreas, and increased gene expression of transcription factors triggering formation of fat cells (adipocyte differentiation), which could be involved in the development of diabetes and obesity, respectively.

In addition, the authors add that recent data show epigenetic changes in the offspring of smoking mothers (meaning the smoking actually causes changes in the gene expression in the unborn child that could predispose them to later obesity or diabetes). They caution though, that unmeasured differences in diet or other factors between families with and without smokers could possibly account for the associations observed.

‘€œAlthough short-term detrimental effects of smoking on the individual and her offspring are well known, such associations might extend into adulthood, making the incentive stronger for undertaking preventable measures, particularly as numbers in some countries point to an increase in daily smoking among young women,’€ conclude the authors.

Source: Diabetologia