A new study from Canada says asthma attacks during pregnancy are associated with an increased risk of health problems for mothers and their babies. Researchers looked at data on more than 100,000 pregnancies from nearly 60,000 women. The women had given birth in Ontario, Canada from 2003 to 2012. All of the women in the study had asthma, but only some had asthma attacks during pregnancy. Asthma is a physical condition that makes breathing difficult. The women who had asthma attacks during pregnancy were 17 percent more likely to have hypertension. They were also 30 percent more likely to have dangerously high blood pressure known as preeclampsia, the study found. They also more often had babies with low weight, preterm babies or babies with birth defects.