| Abstract [eng] |
Rationale. A growing body of evidence suggests that obesity adversely impacts the course of pregnancy and childbirth. Hundreds of observational studies worldwide report associations between obesity and a wide range of pregnancy and childbirth complications. In response to this, an increasing number of meta-analyses synthesizing said primary studies are published each year. This abundance of publications makes it difficult to select the most reliable sources and draw conclusions about the certainty of evidence. Therefore, an overview of meta-analyses is warranted to summarize the findings of meta-analyses, evaluate their quality and the certainty of evidence. Aim. To evaluate the evidence from meta-analyses on the association between obesity and complications of pregnancy and childbirth. Objectives. 1. To assess the methodological quality of meta-analyses using AMSTAR 2. 2. To identify pregnancy and childbirth complications associated with obesity. 3. To evaluate the strength of these associations. 4. To assess the presence of a dose-response relationship between body mass index (BMI) and complications. 5. To determine the certainty of evidence using an adapted GRADE approach. Methods. A systematic overview of meta-analyses was conducted. Literature searches were performed in PubMed, Scopus and Web of Science using MeSH terms and free-text keywords. Studies were selected according to predefined inclusion and exclusion criteria. Data was extracted into MsExcel spreadsheets. Methodological quality was assessed using AMSTAR 2. The strength of associations was evaluated based on effect sizes and their confidence intervals. Dose-response relationships were assessed using BMI category stratified and linear effect estimates. The certainty of evidence was evaluated using an adapted GRADE approach. Results. A total of 41 publications met the inclusion criteria. Of these, 39 were rated as critically low quality, 1 as low quality and 1 as moderate quality according to AMSTAR 2. The included meta-analyses examined associations between obesity and 39 pregnancy and childbirth complications. Strong associations were identified for 4 complications, moderate for 14, and weak for 11. A dose-response relationship with BMI was observed for 18 complications. The certainty of evidence was very low for 29 complications, low for 7, and moderate for 3. Conclusions. Most meta-analyses investigating the association between obesity and pregnancy and childbirth complications have serious methodological flaws. Although obesity is associated with numerous complications, these associations are generally of weak to moderate strength. A dose-response relationship with BMI is observed for a substantial proportion of outcomes. Overall, the certainty of evidence is predominantly very low. |
