Poorly controlled asthma during pregnancy puts mothers and their babies at increased risk for serious complications, a new study finds.
Researchers analyzed more than 100,000 pregnancies in more than 58,000 women with asthma in Canada.
Compared to those whose asthma was well-controlled, women who had severe asthma symptoms during pregnancy were 17% more likely to have high blood pressure and about 30% more likely to develop a serious condition called preeclampsia.
Babies born to women who had asthma attacks during pregnancy were 14% more likely to have a low birth weight; 14% more likely to be premature; and 21% more likely to have an abnormality such as a heart defect or cleft lip.
Children born to mothers who had severe asthma symptoms during pregnancy had 23% higher odds of asthma and a 12% higher odds of pneumonia by age 5, according to the study published recently in the European Respiratory Journal.
The findings are important because up to 40% of women with asthma cut back or stop taking asthma medication during pregnancy because they're afraid it will harm the unborn baby, according to the researchers.
"Asthma is the most common chronic disease in pregnant women, affecting 8-13% of pregnant women worldwide," said study leader Kawsari Abdullah, a research fellow at Children's Hospital of Eastern Ontario in Ottawa.
She was at The Hospital for Sick Children (SickKids) in Toronto when the study was conducted.
"Previous research has shown that one out of every three pregnant women with asthma will suffer severe symptoms, so we need to understand what this means for women and their babies," Abdullah said in a journal news release.
Researcher Teresa To, a senior scientist at SickKids, said the study is the biggest to examine risks associated with several asthma symptoms in pregnancy.
"It's also the first to show the longer-term impacts on children up to the age of 5 years. Our results reinforce the findings of smaller studies that uncontrolled asthma can be bad for mothers and their babies," she said.
To said the findings suggest that severe asthma symptoms pose a bigger risk to mother and fetus than asthma medication itself.
"This study does not explain why asthma attacks contribute to all these health issues, but the likely mechanism is reduced oxygen supply for the mother and subsequently to the baby in the womb," To said.