Page URL:

Overweight women more likely to miscarry healthy babies

17 November 2008
Appeared in BioNews 484

Overweight women are at greater risk of miscarrying a genetically normal baby in the early stages of pregnancy than women who maintain a healthy weight, according to a new study by scientists at the Stanford University School of Medicine in California, US. The researchers, presenting at the annual American Society for Reproductive Medicine (ASRM) conference, suggested that this indicates that a mother's weight can affect the outcome of an otherwise healthy pregnancy.

The UK's NHS estimates that around a quarter of all pregnancies in the UK end in miscarriage. The majority of these occur in the first 12 weeks of pregnancy, but can occur up to 24 weeks. The cause of miscarriage is not always known, but it is thought that between 50 and 70 per cent occur as a result of chromosomal abnormalities (genetic defects) in the fetus. The California researchers tested DNA from 204 fetuses miscarried in the first eight weeks of pregnancy. They compared the rate of chromosomal abnormalities in the fetuses from women with a normal body mass index (BMI) with the rate of abnormalities in fetuses from women with a BMI that classified them as overweight or obese. They found that 53 per cent of babies lost by overweight women had no chromosomal abnormalities compared to just 37 per cent of babies lost by women of a more healthy BMI.

Dr Inna Landres, who led the research team, said that these findings indicate that 'obesity predisposes women to miscarry normal babies.' The reason for this is not yet understood, but Dr Landres suggested that one explanation could be altered levels of hormones such as oestrogen and androgens seen in overweight women. She emphasised: 'It's important to identify elevated BMI as a risk factor for miscarriage and counsel those women who are affected on the importance of lifestyle modification.'

An individual's BMI is calculated by dividing their weight in kilograms by their height in metres squared. A BMI of 18 to 25 is considered normal, whilst over 25 is classed as overweight and over 30 as obese. All the women in the current study were attending an academic centre for fertility counselling and had their BMI calculated before conception.

Dr Mark Hamilton, chairman of the British Fertility Society (BFS), said: 'It is recognised that women who are overweight are at a greater risk of miscarriage. It has not been defined if that risk is related to genetic problems for the embryos or the obesity itself is linked to implantation mechanisms. This study will aid our understanding of the known association with being overweight and reproductive loss.'

Fat mums 43 per cent more likely to miscarry
The Mirror |  14 November 2008
Obese women 'more likely to miscarry'
The Guardian |  14 November 2008
Overweight women at greater risk of miscarriage
The Daily Telegraph |  14 November 2008
4 January 2009 - by Sarah Pritchard 
The results of a study in Scotland have indicated that obese and overweight women have the same chance of successful IVF treatment as normal weight women. The research was undertaken in Aberdeen between 1997 and 2006, on 1,700 women undergoing their first cycle of IVF, and included...
8 September 2008 - by Dr Rachael Panizzo 
By Rachael Dobson: Researchers at the Salk Institute in La Jolla, California, US have found that the TORC1 gene in the brain controls both appetite and fertility. TORC1 acts as a 'master switch' that, when turned on, reduces food intake and allows pregnancy to occur, they report in the journal...
17 December 2007 - by Ailsa Stevens 
Overweight women are significantly more likely to experience fertility problems, according to a study published in the journal Human Reproduction last week. Obesity is defined in adults as having a body mass index (BMI) above 30. The study found that for every BMI unit above 29, the...
19 November 2007 - by MacKenna Roberts 
Severely obese women should have their fertility treatment deferred until they have lost weight, according to new guidance issued by the British Fertility Society (BFS), based upon their comprehensive analysis of studies which establish the adverse impact of obesity on fertility. The report, published in the BFS...
28 August 2007 - by Katy Sinclair 
By Katy Sinclair: A Lancet report has warned that the soaring levels of obesity in the western world will lead to a major infertility crisis in women. Commenting on the findings, Bill Ledger, Professor of Obstetrics at the University of Sheffield, warned that in the next decade the number of...
10 April 2007 - by Zulehkha Waheed 
Obese women should have fertility treatment withheld, according to a report from a leading group of Scottish doctors. Their recommendation is an attempt to reduce growing costs within the National Health Service (NHS), where resources are already over-stretched. According to the Scottish Committee of the Royal College...
to add a Comment.

By posting a comment you agree to abide by the BioNews terms and conditions

Syndicate this story - click here to enquire about using this story.