Interpregnancy Weight Change and Risks of Stillbirth and Infant Mortality: a Protocol of a Systematic Review and Meta-Analysis.

Introduction Interpregnancy weight change may impact two important adverse perinatal outcomes: stillbirth and infant mortality. This systematic review aims to synthesise the existing evidence on the association between interpregnancy weight change and stillbirth and infant mortality.Methods and analysis This systematic review and meta-analysis will be conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses Protocols guidelines and has been registered in the International Prospective Register of Systematic Reviews (PROSPERO). A comprehensive literature search of four online databases (Embase, Cochrane Libraries, Web of Science and Medline) will be conducted from inception to October 2023. Observational (longitudinal, cohort, case–control) and randomised controlled trials will be included. Interpregnancy weight/body mass index change between two consecutive pregnancies will be the exposure. The primary outcomes will be the incidence of stillbirth and infant mortality in subsequent pregnancy. The Cochrane Risk of Bias tool will be used to assess the risk of bias in the randomised controlled studies and the Risk of Bias in Non-Randomised Studies of Interventions tool will be used for observational studies. If there are sufficient data, a meta-analysis will be conducted to estimate the pooled effect size. Otherwise, qualitative descriptions of individual studies will be summarised. The heterogeneity will be statistically assessed using a χ2 test and I2 statistic.Ethics and dissemination Ethics approval is not required for this study as all results will be based on published papers. No primary data collection will be needed. Study findings will be presented at scientific conferences or published in a peer-reviewed scientific journal.Trial registration number A registration for this review has been submitted to PROSPERO under CRD42020222977.