Obesity is a common problem among women of reproductive age. Twenty-six percent of women in the UK have a body mass index (BMI) of more than 30 kg/m2. Female patients outnumber male patients seeking bariatric surgery by a ratio of around 3:1 and approximately 70% of these women are of childbearing age. In one study, 25% (29/115) of women presenting for bariatric surgery suffered from infertility.
Obesity has a negative impact on natural conception, pregnancy and the long-term health of mother and child due to an increased rate of congenital anomalies, pregnancy complications and the possibility of metabolic disease in later life; and the likelihood of miscarriage in obese women who do conceive is raised.
Women who are obese respond less well to drugs used for ovarian stimulation for the treatment of anovulation and assisted conception, although this does not always equate with reduced ongoing pregnancy rates. Obesity may affect the technical feasibility of clinical procedures such as visualising the ovaries on ultrasound scan or oocyte retrieval. Obesity affects oocyte and embryo health and may also affect endometrial receptivity. Whereas autologous in vitro fertilisation (IVF) in obese women results in fewer live births, donor egg pregnancies in obese women have been shown in one meta-analysis of six studies to result in safe births, suggesting that it is the quality of the oocyte, and not necessarily the reproductive environment that is affected by obesity. On the other hand, some authors have shown that obesity may influence the receptivity of the uterus.
Pregnancy in obese women can precipitate metabolic illness and is associated with obstetric risks. In the largest study of its kind of 16,000 women, a maternal BMI of greater than 30 kg/m2 was associated with an increased risk of gestational diabetes, gestational hypertension, pre-eclampsia and fetal macrosomia compared with women with a BMI of less than 30 kg/m2. Induced labour and caesarean delivery, anaesthetic complications, perioperative morbidity and longer hospital stays are more prevalent in obese women.
The effective ways to induce long-term weight reduction in women with severe obesity are either significant sustained lifestyle changes, which are not achieved by most very obese people in the long term, or bariatric surgery. National Institute for Health and Care Excellence (NICE) guidelines recommend that bariatric surgery be considered when the BMI is 40 kg/m2 or more, or for those with a BMI between 35 and 40 kg/m2 in the presence of other comorbidities and where other nonsurgical methods have proven unsuccessful.
Declaration of interests (guideline developers)
Dr S Scholtz MBChB MRCPsych Dip (CBT) PhD, London: None declared.
Professor AH Balen FRCOG, Leeds: Professor Balen has acted as a consultant for ad hoc advisory boards for Ferring Pharmaceuticals, Astra Zeneca, Pharmasure, Merck Serono, Gideon Richter and Uteron Pharma. He has been paid for manuscript preparation by these companies and by various universities and societies. He provides expert reports in medical negligence cases for which the fee is paid by the instructing solicitors. Professor Balen's research is largely funded by public bodies in the UK and European Union, although he has occasionally participated in research projects where pharamaceutical companies have contributed a grant. He has received honoraria and had travel and accomodation expenses covered or reimbursed for speaking at meetings by the pharmaceutical companies listed above, various colleges, universities and societies, and public research funding bodies. His institution has received sponsorship for organising education meeting and he receives royalties on his books from publishers.
Professor CW le Roux MBChB, MSC, FRCP, FRCPath, PhD, Dublin: Professor le Roux has received honoraria for contribution to advisory boards for Novo Nordisk, Herbalife, Johnson & Johnson, Covidien, Fractyl and GI Dynamics.