Pregnant women with asthma should take special care to keep their asthma in check.

Canadian researchers have found that asthma attacks during pregnancy are associated with a number of serious health problems for both mother and child.

The observational study, in The European Respiratory Journal, used data on 103,424 pregnancies in women with asthma. Exacerbations — shortness of breath, wheezing, coughing or chest tightness — that required medical attention occurred in 4,455 of the pregnancies.

After adjusting for other factors, compared with women who had no exacerbations, those who did had a 30 percent increased relative risk for pre-eclampsia, the dangerously high blood pressure of pregnancy. They also had a 14 percent increased risk for having a low birth weight baby, a 14 percent increased risk for preterm birth, and a 21 percent increased risk for having a baby with a congenital malformation.

Asthma attacks in mothers were also tied to lingering consequences for offspring. The researchers found that compared with the children of mothers who had no exacerbations, the children of mothers who did had a 22 percent increased risk for asthma and a 12 percent increased risk for pneumonia through age 5.

“Based on this research, I can’t say whether women should take medication or not,” said the lead author, Kawsari Abdullah, a postdoctoral researcher at the Children’s Hospital of Eastern Ontario. “The important thing is that they need to control their symptoms and follow the guidelines their physicians provide.”