Genes linked to smoking in pregnancy identified

Researchers have identified a genetic link to smoking in pregnancy.

The study also showed men experience more long-lasting effects when their mother smokes while pregnant than women – including dying younger if they go on to smoke themselves.

A team of researchers from the University of Aberdeen studied more than half a million people across the UK to understand the effects of smoking in pregnancy and how they can persist throughout adulthood.

The group, led by Professor Paul Fowler, chairman in translational medical sciences at the university, used the genetic relationship between mothers and their adult children to conduct the first large-scale genetic analysis of maternal smoking.

They identified several gene variants that increase the likelihood of maternal smoking, opening up potential to develop more targeted treatments to stop people smoking.

Using data from 500,000 people across 22 centres in Scotland, England and Wales, the team were able to investigate the genetic, biochemical and socio-demographic factors associated with smoking during pregnancy.

This manifested as changes in levels of various genes in male fetal livers as early as at 17 weeks pregnant right through to adult males having shorter life expectancy.

The team found if the adult man stops smoking, or did not smoke at all, they can counter these risks.

The increased likelihood for an early death was reduced in men who reported to have never smoked cigarettes themselves.

The new insight could help devise more effective strategies to mitigate the adverse effects of maternal smoking exposure.

The study also found men are more likely to develop cancer in adulthood and are more susceptible to developing type two diabetes than females.

Women are more likely to develop digestive and reproductive disorders as well as mental health issues.

Postgraduate researcher Mihail Mihov, who conducted the research as part of their PhD studies, said: “Maternal smoking during pregnancy has been linked to many health issues for babies.

“However, we previously had limited knowledge about which processes in the womb are influenced by maternal smoking and how they translate to diminished health later in life.

“Our findings show that maternal smoking impacts baby’s health, particularly for males, from as early as the second trimester and this continues throughout adulthood.

“We also, for the first time, identified several gene variants which increase the likelihood that a mother will smoke or be addicted to smoking, even during pregnancy.

“This opens avenues where we can look for potentially gene-specific targetable pathways to smoking cessation and therefore offer ways to decrease the societal burden of maternal smoking in our ageing society.”

Felix Grassmann, professor of epidemiology and biostatistics at the Health and Medical University in Potsdam, Germany, who co-led the research, said: “Most research has been conducted in cohorts with too few individuals thus lacking statistical power to uncover the rarer associations.

“In this research, we used the UK Biobank cohort which has genetic, biochemistry and medical questionnaire data on more than 500,000 individuals making it one of the biggest studies reported on the effects of maternal smoking during pregnancy.

“In short, we found that when a mother smokes during pregnancy her son’s liver is more affected than her daughter’s liver.

“This difference and the sex difference in risk of death continues into middle age.”

Prof Fowler said: “We hope our findings will pave the way towards investigating the molecular effects of maternal smoking which will allow the scientific community to uncover the specific mechanisms by which the trait modifies or initiates specific diseases.

“Ultimately, we also hope it helps the medical community to develop even better counselling strategies and campaigns towards smoking cessation.”

Sheila Duffy, chief executive of the health charity Action on Smoking and Health Scotland, said: “We welcome this research as its world leading insights are valuable and will help to better inform parents and communities about exposure to tobacco during pregnancy harming not only the mother and baby, but also spotlighting that the harmful impacts persist into seriously damaging children’s lives into adulthood.

“Tobacco is utterly toxic and it is vital that we support people to move away from it, something many parents are especially keen to do during pregnancy.

“This study shows that tobacco toxins damage genes and human development in ways we are only starting to understand.”