Asthma raises risk of perinatal complications

Pregnant women with asthma have a significantly increased risk of adverse perinatal outcomes, including preeclampsia, preterm delivery, and low birthweight, suggests a meta-analysis published online July 13 in BJOG: An International Journal of Obstetrics and Gynaecology.

Australian and American researchers reviewed 40 studies published between 1975 and 2009 involving 1,637,180 pregnant women. They found that women with asthma had a higher risk than women without asthma of preeclampsia (relative risk [RR], 1.54), low birthweight (RR, 1.46), preterm delivery (RR, 1.41), and small for gestational age infants (RR, 1.22). Infants of women with asthma weighed an average of 93 g less than those born to women without asthma. Asthma raised the risk of preeclampsia by at least 50% and preterm birth by around 25%. However, active asthma management reduced the risk of preterm labor and delivery to nonsignificant levels.

“Exacerbations are key events that may contribute to poor perinatal outcomes, and are common in pregnancy,” the authors of the study write, citing risk factors such as asthma severity, viral infection, poor adherence to control regimens, and obesity. They researchers recommend monitoring asthma in pregnant women at least once a month because changes in the condition can be unpredictable during pregnancy and may not be consistent from one pregnancy to the next in the same woman.

The investigators suggest 3 main explanations for increased perinatal risk in women with asthma: chronic maternal hypoxia, a “common pathogenesis” for severe asthma and perinatal complications, and a direct adverse effect on mother or fetus of asthma medications. However, they note with regard to medications that “the preponderance of the evidence to date suggests that commonly used asthma medications, such as inhaled corticosteroids and inhaled short-acting β-agonists, do not increase perinatal risk, and that treatment with inhaled corticosteroids may actually be protective against outcomes such as low birthweight.”