Women who smoke during pregnancy may be increasing their child’s risk of developing attention-deficit/hyperactivity disorder (ADHD), according to a new study conducted by the Research Centre for Child Psychiatry at the University of Turku in Finland.
For the study, the researchers measured levels of cotinine — the predominant metabolite in nicotine — in the mother’s blood during pregnancy. The findings show that higher blood levels of cotinine were tied to a greater risk for the child’s later development of ADHD.
The study is the first to link prenatal nicotine exposure and ADHD by measuring cotinine levels in maternal blood samples.
“All previous studies on the topic were based on maternal self-report of smoking that has been shown to underestimate the true rates of smoking. The disclosure of smoking is even lower among pregnant smokers,” said Adjunct Professor Roshan Chudal from the Research Centre for Child Psychiatry at the University of Turku.
For the study, cotinine was used as a biomarker for nicotine exposure. Nicotine exposure includes active smoking as well as exposure from other sources such as nicotine replacement therapy or passive smoking.
The research involved 1,079 ADHD cases and an equal number of matched controls born between 1998 and 1999. Maternal cotinine levels were measured from maternal serum specimens collected during the first and second trimesters of pregnancy and archived in Finland’s national biobank.
“In this first nationwide study using maternal cotinine levels, we report a strong association between prenatal nicotine exposure and offspring ADHD,” said Professor Andre Sourander, the leader of the research group from the Research Centre for Child Psychiatry.
The World Health Organization (WHO) considers smoking one of the main public health concerns worldwide. Despite its proven negative effects on fetal development, smoking during pregnancy remains a significant public health issue.
In 2016, 7.2 percent of women in the United States who gave birth smoked cigarettes during pregnancy, according to the Centers for Disease Control and Prevention (CDC). Prevalence of smoking during pregnancy was highest for women aged 20 to 24 (10.7 percent), followed by women ages 15 to 19 (8.5 percent) and 25 to 29 (8.2 percent).
In Finland, where the research took place, the numbers are higher. During 2017, approximately 12.5 percent of all pregnant women in Finland smoked during pregnancy and 7 percent continued to smoke throughout their pregnancy.
“Given the high prevalence of both smoking during pregnancy and ADHD among children, these findings warrant future studies on the interplay between maternal smoking and environmental, genetic, and epigenetic factors,” said Sourander.
Source: University of Turku