Obesity is not a threat to successful IVF

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 overweight women, and women who were clinically and heavily obese. No marked difference was noted in the proportion of positive pregnancy tests, ongoing pregnancies and live births between any particular weight group. In addition, no further cost was incurred by women with a body mass index (BMI) of up to 35 (individuals with a BMI of over 25 are classed as overweight, while those over 30 are classed as obese).

However, the study showed that a higher proportion of women in the overweight and obese groups had a miscarriage and needed higher doses of drugs to stimulate their ovaries during their treatment. The higher rate of miscarriage echoes the findings of a study conducted last November by scientists at the Stanford University School of Medicine in California, US, which suggested that a mother's weight can affect the outcome of an otherwise normal pregnancy.

Leader of the study Dr Abha Maheshwari, a clinical lecturer in reproductive medicine at the University of Aberdeen, said that women with a BMI over 35 should not be offered IVF until they had lost weight because of the particularly high risk of complications. Professor Adam Balen, an expert in reproductive medicine at Leeds Teaching Hospitals agreed, saying that there is no doubt that obesity has a powerful effect on fertility. Balen also recognised that the risk of complications such as miscarriage and maternal or fetal death are more readily associated with obesity.

Dr Maheshwari had expected IVF costs to be higher in overweight and obese women, but the study showed that treatment should not be declined based on weight alone and that age was a much more relevant factor. The British Fertility Society recommends that no one with a BMI over 35 should receive IVF treatment, and women with a BMI over 30 should delay treatment until they have lost weight. Professor Balen, author of the Society's guidelines, emphasised that these were put together on clinical grounds, not cost grounds.