British Fertility Society issues new guidelines on the effect of obesity on female reproductive health

The British Fertility Society has issued new guidelines for the treatment of women with fertility problems according to their weight.  This follows a thorough review of the evidence regarding the interaction between obesity and female reproduction.  The British Fertility Society is committed to promoting good clinical practice and working with patients to provide safe and effective fertility treatment.  These guidelines are designed to help more women who currently suffer from infertility to become pregnant with minimum risk to their health and that of the child.

To summarise, the guidelines state:

  • Obesity has a significant adverse effect on female reproductive health.
  • Being obese decreases the chances of natural conception, reduces the likelihood that fertility treatment will be successful and increases the risk of miscarriage, congenital anomalies and pregnancy complications.  Obesity also decreases the safety of fertility procedures, for example the ability to see ovaries on ultrasound scan or the provision of safe anaesthesia.  In addition, obesity can have negative long-term health effects on both the mother and the child.
  • All women should be advised to achieve a weight appropriate to their height before embarking on pregnancy.  Women seeking fertility treatment should likewise aim to achieve a Body Mass Index (BMI) in the normal range.  In clinical practice, treatment should normally be deferred if the BMI is in excess of 35.  Patients below 37 years of age, and where the clinical circumstances permit, should be encouraged to reduce their BMI to less than 30 to maximise effectiveness and reduce risks of treatment.
  • Clinicians should inform their patients about the negative effects of extra weight on their chances of conceiving naturally.  Clinicians should consider deferring the provision of fertility treatment to women whose weight lies outside the guidelines outlined above.
  • Women should be provided with assistance to lose weight, including psychological support, dietary advice, exercise classes and, where appropriate, weight reducing agents or bariatric surgery.  Even a moderate weight loss of 5-10% of body weight can be sufficient to restore fertility.

Mr Tony Rutherford, Chair of the British Fertility Society’s Policy and Practice Committee, said:

The British Fertility Society wants to ensure that all women receive the safest treatment when undergoing fertility procedures, while also maximising their chances that the treatment will be successful.  Obesity reduces the chances that a woman will conceive naturally and decreases the possibility that fertility treatment will be successful.  It also increases the risk of complications during fertility treatment and pregnancy and endangers the health and welfare of both mother and child.

Following a thorough analysis of the evidence, the BFS has produced these new guidelines to help doctors provide safer and more effective fertility treatment for women.  We want to work with our patients to improve their chances of becoming pregnant with minimum risk to their health and that of their child.  The BFS would also like to see more resources put towards supporting and helping women to lose weight to improve their chances of conceiving.”


Comment from Infertility Network UK

Infertility Network UK welcomed the new guidelines and endorsed the recommendation that patients seeking fertility treatment yet needing to lose weight should receive more help and support to do so.

Chief Executive of Infertility Network UK Clare Brown said:

It should be remembered that there are conditions affecting your fertility which also have an impact on your weight plus women are under a great deal of stress when battling with infertility.  We hope these new guidelines will both inform patients as well as encourage clinicians to help and support them in their efforts to lose weight.  We would also recommend that clinicians adopt a flexible approach where possible and look at cases on an individual basis.


General information

Obesity is a common health problem among women of reproductive age, with 56% of women in the UK being either overweight or obese.  According to current World Health Organisation guidelines, normal BMI is defined as 19-24.9 kg/m2, overweight BMI as 25.0-29.9kg/m2, moderate obesity BMI as 30.0-34.9kg/m2, severe obesity BMI as 35.0-39.9kg/m2 and very severe obesity BMI as >40kg/m2.

These guidelines are aimed at all health professionals and service providers involved in the care of obese women before and during pregnancy.


For more information: please contact the British Fertility Society press office


Abstract

Impact of Obesity on female reproductive health: British Fertility Society, Policy and Practice Guidelines

Adam H. Balen1 & Richard A Anderson2 for the Policy & Practice Committee of the BFS

1Reproductive Medicine & Surgery, Leeds Teaching Hospitals, Leeds, UK and 2Division of Reproductive and Developmental Science, Centre for Reproductive Biology, University of Edinburgh, Edinburgh, UK.

Obesity has a significant adverse impact on reproductive outcome. It influences not only the chance of conception but also the response to fertility treatment, and increases the risk of miscarriage, congenital anomalies and pregnancy complications in addition to potential adverse effects on long term health of both mother and infant. Women should aim for a normal BMI before starting any form of fertility treatment. Treatment should be deferred until the BMI is less than 35 kg/m2, although in those with more time (e.g., less than 37 years; normal serum FSH concentration) a weight reduction to a BMI of less than 30 kg/m2 is preferable. Clinicians should consider deferring treatment to women outside these guidelines. Women should be provided with assistance to lose weight, including psychological support, dietary advice, exercise classes and where appropriate, weight reducing agents or bariatric surgery. Even a moderate weight loss of 5–10% of body weight can be sufficient to restore fertility and improve metabolic markers.