Maternal prepregnancy obesity and the risk of shoulder dystocia: a meta-analysis.

BACKGROUND

Results from epidemiological studies about the association between maternal prepregnancy obesity and the risk of shoulder dystocia are inconsistent.

OBJECTIVE

To evaluate the effect of maternal prepregnancy obesity on the risk of shoulder dystocia.

SEARCH STRATEGY

We searched PubMed and the Web of Science database for all relevant studies up to 5 August 2016 and reviewed the reference lists of identified articles.

SELECTION CRITERIA

Observational studies that investigated the association between prepregnancy obesity and the risk of shoulder dystocia were included.

DATA COLLECTION AND ANALYSIS

A total of 20 articles involving 2 153 898 participants were included in this meta-analysis. A random-effects model was used to calculate the pooled relative risks (RRs) with 95% CIs.

MAIN RESULTS

For obese versus nonobese, the pooled RR of shoulder dystocia was 1.63 (95% CI: 1.33-1.99). The findings remained significant in the cohort studies (RR = 1.57, 95% CI: 1.28-1.93) and case-control studies (RR = 2.70, 95% CI: 1.46-4.98). With regard to the subgroup 'continents', there was a significant association between obesity and the risk of shoulder dystocia in Europe (RR = 1.51, 95% CI: 1.18-1.92) and Asia (RR = 2.59, 95% CI: 1.15-5.83). The result from the sensitivity analysis for studies adjusted for gestational diabetes was significant (RR = 1.61, 95% CI: 1.05-2.47). The pooled RRs for obesity classes I, II and III versus nonobese were 1.29 (95% CI: 1.06-1.57), 1.94 (95% CI: 1.26-2.98) and 2.47 (95% CI: 1.56-3.93), respectively.

CONCLUSION

This meta-analysis suggests that maternal prepregnancy obesity is associated with an increased risk of shoulder dystocia.

TWEETABLE ABSTRACT

A meta-analysis shows that maternal prepregnancy obesity increases the risk of shoulder dystocia.