Smoking | Smoking during pregnancy is risky For Health | Quitting smoking during pregnancy
Mothers who smoke during pregnancy put their children at greater risk of developing psychotic symptoms in their teenage years.
New research reported in the recent issue of the British Journal of Psychiatry shows a link between maternal tobacco use and psychotic symptoms.
Scientists from Cardiff, Bristol, Nottingham and Warwick Universities studied 6,356 12-year-olds from the Avon Longitudinal Study of Parents and Children. All the children completed an interview for psychotic-like symptoms, such as hallucinations or delusions. Just over 11% of the children (734) had suspected or definite symptoms of psychosis.
Smoking during pregnancy was found to be linked to an increased risk of psychotic symptoms in the children. The scientists observed a ‘dose-response effect’, meaning that the risk of psychotic symptoms was highest in the children whose mothers smoked the most heavily during pregnancy.
The study also examined whether alcohol use and cannabis use during pregnancy was linked to a higher risk of psychotic symptoms.
Drinking during pregnancy was linked to increased psychotic symptoms, but only in the children of mothers who had drunk more than 21 units of alcohol a week in early pregnancy. Only a few mothers in the study said they had smoked cannabis during pregnancy, and this was not found to have any significant association with psychotic symptoms.
The reasons for the link between maternal tobacco use and psychotic symptoms are uncertain. But the scientists suggest that exposure to tobacco in the womb may have an indirect impact by affecting children’s impulsivity, attention or cognition. They have called for further studies to investigate how exposure to tobacco in utero affects on the development and function of children’s brains.
It is estimated that between 15 and 20 per cent of women in the UK continue to smoke during their pregnancy.
Dr Stanley Zammit, a psychiatry expert at Cardiff University’s School of Medicine and main author of the study, said “In our cohort, approximately 19 per cent of adolescents who were interviewed had mothers who smoked during pregnancy.
“If our results are non-biased and reflect a causal relationship, we can estimate that about 20 per cent of adolescents in this cohort would not have developed psychotic symptoms if their mothers had not smoked. Therefore, maternal smoking appears to be an important risk factor in the development of psychotic experiences in the population”.
Quitting smoking during pregnancy?
Scientists from the Peninsula Medical School and the University of Bristol, using data from the Avon Longitudinal Study of Parents and Children and the Exeter Family Study of Childhood Health, have identified a common genetic variant that explains why some women may find it more difficult to quit smoking during pregnancy.
Their paper, “A common genetic variant in 15q24 nicotinic acetylcholine receptor gene cluster (CHRNA5-CHRNA3-CHRNB4) is linked to a reduced ability of women to quit smoking in pregnancy”, is published in Human Molecular Genetics
Maternal smoking during pregnancy is linked to low birth weight and problems at birth. Statistically, women are more likely to quit smoking during pregnancy that at any other time in the lives, but some pregnant women continue to smoke despite a strong and direct public health message.
The study tested whether a genetic variant that is correlation to greater cigarette consumption was also responsible for a reduced likelihood of quitting smoking during pregnancy.
The research team studied 7,845 women of European descent from the South West of England. Using 2,474 women who smoked regularly immediately before they became pregnant, the association between the variant and smoking cessation and smoking quantity during pregnancy was analysed.
When asked about smoking in the first trimester of pregnancy, 28% of the women said they had given up. However, this figure was only 21% in the group of women with two copies of the smoking addiction gene, whereas in women with two copies of the non-addictive gene, 31% said they had quit.
Asked again in the third trimester, 47% of women with two copies of the non-addictive gene said they had stopped smoking, compared with only 34% of women with two copies of the smoking addiction gene.
Dr. Rachel Freathy from the Peninsula Medical School commented: “Pregnant women are under considerable health and social pressure to stop smoking, and quitting in such circumstances is influenced by many factors including the age of the expectant mother, their education and whether or not their partners smoke. However, we were keen to investigate whether the genetic variant that influences increased cigarette consumption also had a role to play as an extra hurdle to quitting smoking during pregnancy, and our study suggests that it does”.
Dr. Freathy added: “However, we would not wish our findings to be used as an excuse to avoid giving up smoking during pregnancy. It is clear from our study that a considerable proportion of women did manage to quit smoking, despite inheriting two addiction copies of the gene. We stress the importance for all expectant mothers who smoke to make use of the resources available from their GP surgeries, local PCTs and pharmacists in their bid to quit smoking, for the benefit of their health and the health of their unborn children”.
Professor Tim Frayling, a senior author on the paper, added “There are parallels between our results and those of genetic studies which have implicated appetite-regulatory pathways in obesity. Both quitting smoking and obesity are thought by a number of scientists, health care professionals and policy makers to be a matter of “self-control” and have much social stigma attached. The identification of common genetic variants may help a little to emphasize that physiology plays an important role in ‘socially unacceptable’ phenotypes”.