Exercise During Pregnancy May Reduce Risk of Asthma in Child

A new study has found that regular physical exercise during pregnancy can significantly reduce a child's risk of developing asthma. According to the research, mothers who exercise at least three times a week during pregnancy nearly halve the risk of their child developing asthma compared to those who are less active. The findings, published in Med, are based on data from almost 1,000 mother-child pairs tracked in the Kuopio Birth Cohort study (KuBiCo), which followed participants from pregnancy until the child was seven years old.

The research was conducted by the University of Eastern Finland (UEF), Kuopio University Hospital (KUH), and the Finnish Institute for Health and Welfare (THL). While maternal exercise is already known to benefit both mother and child, including improvements in newborn lung function, this study is the first to show a direct link between exercise during pregnancy and reduced asthma risk in children.

"This is the first time we are observing an association between maternal exercise and the development of asthma in the child," said Doctoral Researcher Emma-Reetta Musakka from the University of Eastern Finland.

The study found that the protective effect of exercise was independent of other maternal health, lifestyle, and environmental factors such as maternal weight, stress, family exercise habits, and even pet ownership. This suggests that the benefits of maternal exercise during pregnancy have a direct, independent impact on the child's future health. "Our findings strongly suggest that maternal exercise during pregnancy has an independent positive effect on the fetus and on the later health of the child," Musakka explained.

One theory is that exercise during pregnancy supports fetal lung development, possibly through increased fetal activity and breathing movements, which play a role in lung maturation. "We don’t yet know why maternal exercise manifests as a reduced risk of asthma in the child, but one possibility is that it supports fetal lung maturation," Musakka noted.

According to researchers, asthma remains the most common chronic illness in children, and many cases could potentially be prevented. Up until now, the primary recommendation for reducing a child's asthma risk has been avoiding cigarette smoke during pregnancy. However, the study’s lead researcher, Pirkka Kirjavainen, PhD, pointed out that maternal exercise may offer a protective effect comparable to that of smoking cessation. "It is intriguing that moderate maternal exercise during pregnancy may have an equally strong protective effect on a child’s asthma risk as if one of the parents quits smoking," Dr. Kirjavainen said.

The study did not find that increasing the frequency of exercise beyond three sessions per week resulted in further reductions in asthma risk. This aligns with current guidelines from the World Health Organization (WHO), which recommend that pregnant women engage in about 2.5 hours of moderate exercise per week. Further research is needed to explore whether different levels or intensities of exercise could enhance asthma prevention.

"The findings are very promising in terms of asthma prevention,” Dr. Kirjavainen said. “It is highly encouraging to see that by engaging in reasonable amounts of exercise, mothers can significantly influence not only their own health, but also the health of their child.”