In their discussion, the authors note that there is a possibility of residual confounding by unmeasured and unknown risk factors. For example gastro-oesophageal reflux disease (GORD) is associated with asthma in adults and asthma in the offspring could be due to GORD (i.e. indication for therapy in the mother) rather than the treatment used; this was only considered in three of the included studies. Other confounders could include maternal characteristics, genetic predisposition for asthma, and other comorbid conditions that might increase a child’s risk of asthma. Therefore, the observed association between acid-suppressive drug use in pregnancy and the risk of childhood asthma should be interpreted cautiously.
Although the researchers caution that this risk be considered by clinicians and parents when deciding whether acid-suppressing drugs should be used during pregnancy, a related editorial advises clinicians “not to jump too quickly to decide that pregnant women should not be taking acid suppressants to prevent asthma in their children”, calling for more careful research into the mechanisms that may be causing the observed associations.