Pregnancy Outcomes among Women with Intermittent Asthma: A Retrospective Cohort Study

Background: It is already known that asthma strongly increases risks of poor pregnancy outcomes. We wonder whether intermittent asthma, the least severe form but accounting for the majority of cases, increases such adverse outcomes or not. Therefore, we conducted this study to compare adverse pregnancy outcomes between pregnancies with intermittent asthma and low-risk pregnancies (controls). Methods: The full medical records of pregnancies with intermittent asthma were comprehensively reviewed and low-risk pregnancies were randomly recruited as controls with a ratio of 10:1. The obstetric outcomes were compared between both groups, and the outcomes in the active subgroup of intermittent asthma (defined as at least one asthmatic attack during pregnancy) were also compared with the controls. Results: Of 364 study cases and 3640 controls, the rates of poor outcomes (preterm birth, preeclampsia, fetal growth restriction etc.) were not significantly different. However, cases with active disease slightly, but significantly, increased the risk of low birth weight. Moreover, mean gestational age was significantly lower in the study group. Conclusions: A new insight gained from this study is that intermittent asthma is not associated with poor pregnancy outcomes, but cases with asthmatic attack during pregnancy tended to increase the risk of preterm birth and low birth weight. This information is important for counseling and the planning of antepartum management.