Maternal drug use during pregnancy and asthma risk among children.

Background: Maternal use of some drugs, notably paracetamol and drugs for gastroesophageal reflux, has been associated with an increased risk of childhood asthma in the child. We wanted to analyze these associations with consideration to the confounding of maternal asthma.

Methods: Childhood asthma was identified from the Swedish National Prescription Register and maternal drug use during the latter part of pregnancy from antenatal records, computerized in the Swedish Medical Birth Register. Risks were estimated as odds ratios (OR) with 95% confidence intervals, using Mantel-Haenszel technique with adjustment for year of birth, maternal age, parity, smoking habits, and BMI.

Results: A statistical association between maternal use of many different drugs, including paracetamol, and childhood asthma existed but was mainly due to concomitant drug use, related to maternal asthma. The only associations that appeared to be true were with drugs for gastroesophageal reflux (adjusted (OR) = 1.32, 95% CI, 1.18-1.54) and with opiates (adjusted OR = 1.56 (96% CI, 1.05-2.34).

Conclusions: Maternal use of paracetamol did not seem to increase the risk of childhood asthma, but the previously described association with drugs for gastroesophageal reflux was supported. The analysis is complicated by the confounding from maternal asthma.