The safety of histamine 2 (H2) blockers in pregnancy: a meta-analysis.

Heartburn and acid reflux increase the severity of nausea and vomiting of pregnancy, and may lead to more serious medical conditions. The fetal safety of histamine 2 (H2) blockers, the most common antireflux medication, during pregnancy needs to be determined. The aim herein is to determine the fetal safety of H2 blockers during pregnancy through systematic review. All original research assessing the safety of H2 blockers in pregnancy was sought. Data included congenital malformations, spontaneous abortions, preterm delivery, and small for gestational age. A random-effects model combined results. With data from 2,398 exposed and 119,892 nonexposed to H2 blockers, overall odds ratio was 1.14 [0.89, 1.45]. Further analysis revealed no increased risks for spontaneous abortions, preterm delivery, and small for gestational age with odds ratios and 95% confidence intervals (CIs) of 0.62 [0.36-1.05], 1.17 [0.94, 1.147], and 0.28 [0.06, 1.22], respectively. H2 blockers can be used safely in pregnancy.