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Research

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

BMJ 2017; 359 doi: https://doi.org/10.1136/bmj.j4511 (Published 26 October 2017) Cite this as: BMJ 2017;359:j4511
  1. Ilkka Kalliala, honorary clinical lecturer1 2,
  2. Georgios Markozannes, research fellow3,
  3. Marc J Gunter, section and group head4,
  4. Evangelos Paraskevaidis, professor5,
  5. Hani Gabra, professor1 6,
  6. Anita Mitra, clinical research fellow1 7,
  7. Vasso Terzidou, clinical senior clinical lecturer1 7,
  8. Phillip Bennett, professor1 7,
  9. Pierre Martin-Hirsch, consultant8 9,
  10. Konstantinos K Tsilidis, assistant professor3 10,
  11. Maria Kyrgiou, clinical senior lecturer1 7
  1. 1Department of Surgery and Cancer, IRDB, Faculty of Medicine, Imperial College, London W12 0NN, UK
  2. 2Department of Obstetrics and Gynaecology, University of Helsinki and Helsinki University Hospital, Haartmaninkatu 2, 00029 HUS, Finland
  3. 3Department of Hygiene and Epidemiology, University of Ioannina School of Medicine, 45110, Ioannina, Greece
  4. 4Section of Nutrition and Metabolism, International Agency for Research on Cancer (IARC), Lyon, France
  5. 5Department of Obstetrics and Gynaecology, University of Ioannina, 45500, Ioannina, Greece
  6. 6Clinical Discovery Unit, Early Clinical Development, AstraZeneca, Cambridge, UK
  7. 7West London Gynaecological Cancer Centre, Queen Charlotte’s and Chelsea-Hammersmith Hospital, Imperial Healthcare NHS Trust, London W12 0HS, UK
  8. 8Department Gynaecologic Oncology, Lancashire Teaching Hospitals, Preston PR29HT, UK
  9. 9Department of Biophysics, University of Lancaster, Lancaster, UK
  10. 10Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London W2 1PG, UK
  1. Correspondence to: M Kyrgiou m.kyrgiou{at}imperial.ac.uk
  • Accepted 14 September 2017

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.

Footnotes

  • We thank Nicola Heslehurst for her assistance in providing missing study specific data.

  • Contributions: MK (joint last author), IK, PMH, EP, and KT (joint last author) conceived and designed the study. IK, MK, and KT acquired and collated the data, which were analysed by IK, MK, GM, and KT. All authors drafted and critically revised the manuscript for important intellectual content. All authors gave final approval of the version to be published and contributed to the manuscript. MK is guarantor.

  • Funding: This work was supported by the Imperial Healthcare NHS Trust NIHR Biomedical Research Centre (P45272 to MK and PB); Genesis Research Trust (Garfield Weston Foundation, P63522 to MK); Ovarian Cancer Action (MK, MG, HG); Sigrid Jusélius Fellowship (P52483 to IK and MK); World Cancer Research Fund International Regular Grant Programme (2014/1180 to KT); and Imperial College Healthcare Charity (P47907 to AM, MK). None of the funders had any influence on the study design; in the collection, analysis, and interpretation of data; in the writing of the report; and in the decision to submit the article for publication.

  • 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.

  • Ethical approval: Not required.

  • Transparency: The lead authors had full access to all the data in the study and the final responsibility for the decision to submit for publication. The lead author affirms that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned have been explained.

  • Data sharing: No additional data available.

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.

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