Hypertensive disorders of pregnancy and risk of asthma in offspring: protocol for a systematic review and meta-analysis

INTRODUCTION: Hypertensive disorders of pregnancy (HDP), one of the most common obstetrical complications, has been reported to have a controversial relationship with the increased risk of asthma in offspring. No systematic review of this topic has been performed. The aim of this systematic review will be to summarise the available evidence examining the association between HDP and the risk of asthma in offspring. METHODS AND ANALYSIS: We will follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and Meta-analysis of Observational Studies in Epidemiology guidelines. A systematic search of the PubMed, Embase, Cochrane and Web of Science databases will be performed using a detailed search strategy from database inception through 31 December 2019. Cohort, case-control and cross-sectional studies that report a diagnosis of maternal HDP and asthma in offspring will be included. Studies will be limited to the English language and include only human participants. Two independent reviewers will conduct the study selection, data extraction and risk of bias assessments using a standardised data extraction form. A meta-analysis will be performed to calculate overall pooled estimates using the generic inverse variance method. The data will be synthesised by either fixed-effect or random effects models according to heterogeneity tests. All analyses will be performed in Stata 14 and RevMan 5.3. High-quality evidence of the relationship between HDP and the risk of asthma in exposed offspring will be identified through the synthesis of current studies. In addition, the results of subgroup analyses and related secondary outcomes will be reported. The following will be concluded: (i) whether HDP increases the risk of asthma in offspring, (ii) whether HDP affects the severity of asthma in exposed offspring and (iii) whether possible differences in the risk of asthma among different HDP subgroups exist. ETHICS AND DISSEMINATION: There is no requirement for ethics approval because the meta-analysis and systematic review will be based on published data. It is anticipated that the dissemination of results will take place at conferences and through publication in a peer-reviewed journal.