Association of urinary bisphenol A concentrations with in vitro fertilisation outcomes: a systematic review and meta-analysis protocol

INTRODUCTION: Bisphenol A (BPA) is a common environmental endocrine disruptor. BPA has been reported to be associated with female infertility, which may not only affect natural pregnancy and natural fertility but also affect the outcomes of in vitro fertilisation (IVF). BPA exposure may help to partly explain the unsatisfactory IVF outcomes, but the relationship between the concentrations of BPA in urine and IVF outcomes remains controversial. Therefore, we will perform a meta-analysis to identify and review the relationship between urinary BPA concentrations and IVF outcomes. METHODS AND ANALYSIS: A comprehensive literature search will be performed in PubMed, Web of Science and the Cochrane central register of controlled trials for relevant articles using MeSH terms and related entry terms (up to 20 April 2022). The language will be restricted to English. Articles will be screened for inclusion in or exclusion from the study independently by two reviewers after removing the duplicates. The titles and abstracts followed by full-text screening will also be conducted independently by two reviewers. In addition, the references of the included literature will also be traced to supplement our search results and to obtain all relevant literature. The Newcastle-Ottawa Scale will be used to assess the methodological quality of the included studies using a star rating system ranging from 0 to 9 stars. Heterogeneity in estimates from different articles will be quantified, and publication bias will be investigated using funnel plots. Finally, a sensitivity analysis will also be conducted to estimate whether our results could have been markedly affected by a single included study. ETHICS AND DISSEMINATION: Ethical approval is not required for this protocol, as participants are not included. Findings will be disseminated through peer-reviewed publications and conference presentations.