Prepregnancy asthma and the subsequent risk of central nervous system defects in offspring

The relationship between childhood asthma and central nervous system defects in offspring is poorly understood. We assessed if childhood asthma was associated with the risk of having an infant with neural tube or other nervous system defects compared with asthma during pregnancy.

We analyzed a longitudinal cohort of 128,060 women who were 5 years or less at study entry and later delivered an infant in Quebec, Canada (1989-2014). We identified women hospitalized for asthma before pregnancy, including childhood and adolescence, and determined if asthma was present during pregnancy based on obstetric records. Main outcomes were neural tube and non-neural tube defects in pregnancy. We used log-binomial regression models to determine risk ratios (RR) and 95% confidence intervals (CI) for the association between asthma and risk of nervous system defects, adjusting for patient characteristics.

Asthma was associated with a greater risk of neural tube defects in offspring (RR 2.39, 95% CI 1.03-5.53) compared with no asthma, but not non-neural tube defects (RR 1.10, 95% CI 0.71-1.71). Women whose asthma resolved before pregnancy had a greater risk of neural tube defects (RR 3.43, 95% CI 1.35-8.69), while women with asthma during pregnancy were at greater risk of non-neural tube defects, especially microcephaly (RR 2.80, 95% CI 1.23-6.40).

Asthma that resolved before pregnancy was associated with an increased risk of neural tube defects in offspring but not non-neural tube defects. Further investigation is needed to determine the pathophysiology connecting childhood asthma with nervous system defects in offspring.