Maternal Medication Use and Childhood Cancer in Offspring - Systematic Review and Considerations for Researchers.

Cancer is an important cause of childhood mortality, yet the etiology is largely unknown. A combination of pre- and postnatal factors is thought to be implicated, including maternal medication use. We aimed to provide 1) a systematic review of peer-reviewed publications on associations between maternal medication use and childhood cancer with a focus on study design and methodology, and 2) suggestions for how to increase transparency, limit potential biases, and improve comparability in studies on maternal medication use and childhood cancer. We conducted a systematic search in the PubMed, Embase, Scopus, Cochrane, and Web of Science databases until June 8th 2020. Altogether, 112 studies were identified. The reviewed studies were heterogeneous in study design, exposure, and outcome classification. In 21 studies (19%), the outcome was any childhood cancer. Of the 91 papers that reported on specific types of cancer, 62% did not report the cancer classification system. The most frequently investigated medication groups were sex hormones (46 studies, excluding fertility medications), and anti-infectives (37 studies). Suggestions for strengthening future pharmacoepidemiological studies on maternal medication use and childhood cancer relate to choice of cancer classification system, exposure windows, and methods for identification of -, and control for, potential confounders.