Asthma attacks during pregnancy are associated with an increased risk of complications for mothers and their babies, a Canadian study suggests.

Nearly 40% of pregnant women decrease or stop taking asthma medication because they are worried that it could be harmful to their unborn babies,” senior study author Teresa To of the Hospital for Sick Children in Toronto and the Children’s Hospital of Eastern Ontario Research Institute in Ottawa said in a statement.

However, the  study indicates that severe asthma symptoms present the greater risk to mother and baby, explains To.

The study followed mothers and babies for 5 years

Asthma is the most common chronic disease encountered in pregnancy, occurring in up to 13% of pregnancies, To and colleagues write in the European Respiratory Journal.

Researchers examined data on more than 103,000 pregnancies among more than 58,000 women with asthma who had babies in Ontario, Canada. The research was carried out from 2003 to 2012.

For the current study, researchers followed women through pregnancy then followed their babies for up to five years.

Compared to women who didn’t have asthma attacks during pregnancy, those who did were 17% more likely to have pregnancy-induced hypertension and 30% more likely to have dangerously high blood pressure known as preeclampsia, the study found.

Low birth weight

The study found out the following asthma-related consequences:

• Low birth weights occurred in 6.8% of pregnancies with asthma attacks, compared with 5.3% of other pregnancies, the study also found.
• Preterm births occurred in 8.2% of pregnancies involving asthma attacks compared with 6.7% of other pregnancies.
• When women had asthma attacks during pregnancy, their children were also more likely to experience allergies and respiratory infections like pneumonia.
• 6.2% of babies had birth defects in pregnancies involving asthma attacks, compared with 5% of infants born to mothers who didn’t have asthma attacks during pregnancy.
• Children were also 23% more likely to develop asthma in early childhood when mothers had asthma attacks during pregnancy. These children were also 12% more likely to have pneumonia during their first five years of life.