Losing weight prior to fertility treatment may not increase obese women's chance of having a baby, according to new research.

A US study found no significant differences in the rate of healthy live births in obese women who lost weight before undergoing fertility treatment, compared to a control group. 

'Although it differs from current clinical standards of care, there's just not enough evidence to recommend preconception weight loss in women with obesity and unexplained infertility,' said lead author Professor Richard Legro, at the Pennsylvania State College of Medicine in Hershey, Pennsylvania.

The study, published in PLOS Medicine, recruited over 300 women aged 18-40 years old, who had at least one year of unexplained infertility and regular ovulation, and whose body mass index (BMI) was 30 or above. BMI is used as a screening tool to determine if an individual has a healthy weight in relation to their height.

The patients were randomised into two groups. One group was put on a weight-loss regimen comprising increased physical activity, a calorie-restricted diet and anti-obesity medication. This resulted in an average weight loss of seven percent. The control group were not guided to lose weight but did increase physical activity. 

These changes were in effect for 16 weeks. Patients who did not conceive naturally during this time were given fertility treatment of up to three cycles of ovarian stimulation and intrauterine insemination. This procedure involves the sperm being delivered directly into the uterus to increase fertilisation success. 

Whilst the weight-loss group did not have increased success in resulting live births compared to the control group, some indicators of health did improve such as lowered blood pressure and a decrease in waist size.

According to the authors, these findings build on the increasing evidence from other studies that preconception weight loss for obese or overweight women before undergoing fertility treatment bears no benefit in improving live birth rates.

Dr Raj Mathur, head of the British Fertility Society and not involved in the study, told MailOnline, 'This study does encourage us to look at the outcome in patients planning IVF treatment, and also whether a rigid cut off BMI of 30 is justified for NHS eligibility purposes.'

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Reproduced from BioNews with permission, a web- and email-based source of news, information and comment on assisted reproduction and human genetics, published by Progress Educational Trust.