CMACE release: National enquiry into maternal obesity - Implications for women, babies and the NHS

Release date: 07/12/2010

The Centre for Maternal and Child Enquiries (CMACE) releases its report Maternal obesity in the UK: Findings from a national project today after its three-year UK-wide national enquiry into Obesity in Pregnancy.

This major national study, which collected information from every maternity unit in the UK, has revealed for the first time the prevalence of severe maternal obesity (body mass index 35+) in the UK. The report also details the complications and consequences of obesity during pregnancy, and outlines the implications for the care of obese pregnant women.  
This study found that around 5% of the UK maternity population were severely obese. In real terms, this equates to around 38,478 (1 in 20) pregnant women each year, and, with growing levels of obesity in the general population, this number is expected to increase. Wales was found to have the highest rate (6.5%, 1 in every 15 pregnant women) of severe maternal obesity in the UK. In England, the region with the highest rate was East of England (6.2%, 1 in every 16 pregnant women), while London had the lowest rates (3.5%, 1 in every 29 pregnant women). 
The report highlighted that pregnancy outcomes for severely obese women are poorer when compared to the general population. The study found that the stillbirth rate in women with a BMI 35+ (8.6 per 1000 singleton births) was twice as high as the overall national stillbirth rate (3.9/1000 singleton births), and that the risk of stillbirth increases with increasing obesity. Also, in women with a BMI 35+, stillbirths occurring during labour and birth were three times higher than the overall national rate in England, Wales and Northern Ireland.   
The risks of obesity in pregnancy extend to the mother too. Pregnant women, and especially obese pregnant women, are more at risk of developing venous thromboembolism (VTE), which is a potentially fatal condition that involves a blood clot forming in a vein which may break away, travel through the circulatory system and obstruct a blood vessel. The CMACE study revealed how VTE risk was poorly documented for obese pregnant women at their first antenatal appointment and fewer than 50% of the women at moderate or high risk of VTE were offered treatment to prevent the condition. For those women who did receive treatment antenatally, the prescribed doses were considered to be insufficient for their body weight, according to current guidelines published by the Royal College of Obstetricians and Gynaecologists (RCOG). Similar findings were found for postnatal treatment for the prevention of VTE, with only 55% of eligible women being prescribed the appropriate medication. These findings highlight that improvements in this area are required to reduce the risk of VTE in obese women during and after pregnancy. 
The CMACE report also revealed that obese women have an increased risk of medical conditions both before and during pregnancy. Thirty-eight per cent of women in the study had at least one medical condition diagnosed prior to and/or during pregnancy. The most common conditions were gestational diabetes and pregnancy induced hypertension, which affect 8-9% of women with a BMI 35+; these conditions affect approximately 2-2.5% of women in the general maternity population. The presence of medical conditions increases the risk of complications for both the mother and baby, and increased surveillance and medical intervention are therefore required.
Only 55% of women with a BMI 35+ gave birth naturally. The caesarean section rate for singleton babies was 37%, which is 1.5 times higher than the rate in the general maternity population. In addition, severely obese women were at least four times more likely to suffer from postpartum haemorrhage within 24 hours of birth than women in the general maternity population. 
The CMACE study also identified gaps in anaesthetic care for obese women. According to current joint CMACE/RCOG guidance, women with a BMI ≥40 (morbidly obese) should receive an antenatal consultation with an obstetric anaesthetist so that potential problems can be identified and an anaesthetic management plan for labour and delivery can be made. Only 45% of eligible women had such a plan.  
A set of ten key recommendations has been developed by CMACE in response to the findings in the report. The purpose of providing these recommendations is to highlight areas requiring better clinical practice. The general points are:
·         Better preconception care and advice is needed for women with overweight and obese BMIs. The joint CMACE/RCOG guideline on managing women with obesity in pregnancy, issued in March 2010, notes that women of childbearing age with a BMI 30+ should be provided with good information and advice on the risks of obesity during pregnancy and childbirth; and they should be supported to lose weight before conception and in the postnatal period. Pre-pregnancy counselling must also include taking an accurate height and weight measurement for a BMI calculation to identify women who may be at further risk or require additional services or care.  
·         Women with obesity have an increased risk of pregnancy complications such as gestational diabetes and pre-eclampsia. CMACE recommends that surveillance and screening according to existing guidelines occur so that referrals for specialist care can be made early in pregnancy. 
·         Women with a BMI 40+ should have a consultation with an obstetric anaesthetist, as recommended by the joint CMACE/RCOG guideline on obesity in pregnancy, so that potential problems such as venous access can be identified before the birth.   
Professor James Walker, Chair of CMACE said, “The numbers of obese mothers are on the rise and this group of women require specialist care since they are more susceptible to illnesses and complications. So far, there hasn’t been a UK-wide study on the extent of the problem but we now have very good data on how these women are cared for and the areas where improvements are urgently needed”. 
Dr Imogen Stephens, CMACE Clinical Director said, “This CMACE report shows that much more needs to be done in the NHS to deal with the growing numbers of obese pregnant women. We have already shown in our previous survey how specialist equipment such as wheelchairs, trolleys and beds are needed to care for this unique group of women. The findings from this new study show that the risks of clinical intervention increase with increasing levels of obesity and that specialist obstetric care is needed. All this requires improved, and better integrated, care for these women”.
Dr Tony Falconer, President of the Royal College if Obstetricians and Gynaecologists (RCOG) said, “Pregnant women who are obese need to know about the associated risks for them and their baby and must be supported to lose weight before they embark on pregnancy. This will involve counselling and advice from a range of healthcare professionals including GPs, midwives, maternity support workers and nutritionists.
When a woman finds out she is pregnant, she tends to adopt positive behaviours to ensure that she is as healthy as she can possibly be and this includes sensible eating and lower alcohol consumption. However, we need to think about being more proactive by encouraging and enabling women to lead healthier lives before they fall pregnant and after giving birth so that they take a more long-term approach to being healthy”.     
ProfessorCathy Warwick, General Secretary of the Royal College of Midwives, said “Our own research backs up these recommendations. Women have told us that they are not getting the level of care that they should from maternity services.
“There is no doubt that being obese and pregnant can leave women open to more problems in pregnancy than non- obese women. However with high quality care these problems can be identified and treated and women can have a very positive experience of pregnancy and birth. It is therefore crucial that midwives and other health professionals work together to ensure that these women get the best possible care, support and advice.  Many women have told the RCM that one of the big barriers to this is that there are simply not enough midwives to spend time with them especially in the antenatal period.
“There is also a much wider and long-term public health message here. There is a real need to reduce obesity in the population as a whole, tackling the issue before women become pregnant.”
To speak to Professor Walker, Dr Stephens, Dr Falconer, or the authors of the report please contact Gerald Chan on 020 7772 6446 or email  To speak to Professor Warwick, please contact Colin Beesley on 020 7312 3432 or
The research lead for this project and author of the report is Dr Kate Fitzsimons (Senior Research Fellow, CMACE). The editor of the report is Professor Ian Greer (Executive Pro-Vice-Chancellor, Faculty of Health & Life Sciences, University of Liverpool; Chair of the National Advisory Committee for CMACE).
To view Maternal obesity in the UK: Findings from a national project, please click here. The launch of the report accompanies the CMACE conference ‘Obesity in Pregnancy: Improving care and effecting change’. To view the conference programme, click here.
This new report follows the publication of the CMACE survey on NHS maternity provision to obese women and the joint CMACE/RCOG clinical guideline ‘Management of Women with Obesity in Pregnancy’ in March this year.
Body mass index (BMI) offers a useful measure of obesity and is a simple index of weight-for-height used to classify underweight, overweight and obesity in adults. BMI is calculated by dividing a person’s weight in kilograms by the square of their height in metres (kg/m2). The table below shows a widely accepted classification published by both the World Health Organization and the National Institute for Health and Clinical Excellence (NICE). This report focused on women with a BMI 35+ (severely obese) in pregnancy.   A woman with a height of 5ft 5” and a weight of 15 stone would have a BMI of 35.
BMI (kg/m2)
Obese I
Obese II
Obese III

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