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

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

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.

Women who had asthma attacks were also 14% more likely to have low-birthweight or preterm babies and 21% more likely to have infants with birth defects.