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Meta-Analysis
. 2017 Oct 26:359:j4511.
doi: 10.1136/bmj.j4511.

Obesity and gynaecological and obstetric conditions: umbrella review of the literature

Ilkka Kalliala  1   2 , Georgios Markozannes  3 , Marc J Gunter  4 , Evangelos Paraskevaidis  5 , Hani Gabra  1   6 , Anita Mitra  1   7 , Vasso Terzidou  1   7 , Phillip Bennett  1   7 , Pierre Martin-Hirsch  8   9 , Konstantinos K Tsilidis  3   10 , Maria Kyrgiou  1   7
Affiliations
Meta-Analysis

Obesity and gynaecological and obstetric conditions: umbrella review of the literature

Ilkka Kalliala et al. BMJ. .

Abstract

Objective To study the strength and validity of associations between adiposity and risk of any type of obstetric or gynaecological conditions.Design An umbrella review of meta-analyses.Data sources PubMed, Cochrane database of systematic reviews, manual screening of references for systematic reviews or meta-analyses of observational and interventional studies evaluating the association between adiposity and risk of any obstetrical or gynaecological outcome.Main outcomes Meta-analyses of cohort studies on associations between indices of adiposity and obstetric and gynaecological outcomes.Data synthesis Evidence from observational studies was graded into strong, highly suggestive, suggestive, or weak based on the significance of the random effects summary estimate and the largest study in the included meta-analysis, the number of cases, heterogeneity between studies, 95% prediction intervals, small study effects, excess significance bias, and sensitivity analysis with credibility ceilings. Interventional meta-analyses were assessed separately.Results 156 meta-analyses of observational studies were included, investigating associations between adiposity and risk of 84 obstetric or gynaecological outcomes. Of the 144 meta-analyses that included cohort studies, only 11 (8%) had strong evidence for eight outcomes: adiposity was associated with a higher risk of endometrial cancer, ovarian cancer, antenatal depression, total and emergency caesarean section, pre-eclampsia, fetal macrosomia, and low Apgar score. The summary effect estimates ranged from 1.21 (95% confidence interval 1.13 to 1.29) for an association between a 0.1 unit increase in waist to hip ratio and risk endometrial cancer up to 4.14 (3.61 to 4.75) for risk of pre-eclampsia for BMI >35 compared with <25. Only three out of these eight outcomes were also assessed in meta-analyses of trials evaluating weight loss interventions. These interventions significantly reduced the risk of caesarean section and pre-eclampsia, whereas there was no evidence of association with fetal macrosomia.Conclusions Although the associations between adiposity and obstetric and gynaecological outcomes have been extensively studied, only a minority were considered strong and without hints of bias.

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Conflict of interest statement

Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.

Figures

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Fig 1 Graphical presentation of main and sensitivity analyses of meta-analyses investigating obesity and gynaecological and obstetric conditions
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Fig 2 Identification and inclusion of observational meta-analyses investigating obesity and gynaecological and obstetric conditions
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Fig 3 Association between summary random effects estimates and inverse of variance in meta-analyses, stratified by type of exposure-outcome pair
See this image and copyright information in PMC

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