Weight reduction intervention for obese infertile women prior to IVF: a randomized controlled trial

STUDY QUESTION: Does an intensive weight reduction programme prior to IVF increase live birth rates for infertile obese women? SUMMARY ANSWER: An intensive weight reduction programme resulted in a large weight loss but did not substantially affect live birth rates in obese women scheduled for IVF. WHAT IS ALREADY KNOWN: Among obese women, fertility and obstetric outcomes are influenced negatively with increased risk of miscarriage and a higher risk of maternal and neonatal complications. A recent large randomized controlled trial found no effect of lifestyle intervention on live birth in infertile obese women. STUDY DESIGN, SIZE, DURATION: A prospective, multicentre, randomized controlled trial was performed between 2010 and 2016 in the Nordic countries. In total, 962 women were assessed for eligibility and 317 women were randomized. Computerized randomization with concealed allocation was performed in the proportions 1: 1 to one of two groups: weight reduction intervention followed by IVF-treatment or IVF-treatment only. One cycle per patient was included. PARTICIPANTS/MATERIALS, SETTING, METHODS: Nine infertility clinics in Sweden, Denmark and Iceland participated. Women under 38 years of age planning IVF, and having a BMI >= 30 and <35 kg/m(2) were randomized to two groups: an intervention group (160 patients) with weight reduction before IVF, starting with 12 weeks of a low calorie liquid formula diet (LCD) of 880 kcal/day and thereafter weight stabilization for 2-5 weeks, or a control group (157 patients) with IVF only. MAIN RESULTS AND ROLE OF CHANCE: In the full analysis set (FAS), the live birth rate was 29.6% (45/152) in the weight reduction and IVF group and 27.5% (42/153) in the IVF only group. The difference was not statistically significant (difference 2.2%, 95% CI: 12.9 to -8.6, P = 0.77). The mean weight change was -9.44 (6.57) kg in the weight reduction and IVF group as compared to + 1.19 (1.95) kg in the IVF only group, being highly significant (P < 0.0001). Significantly more live births were achieved through spontaneous pregnancies in the weight reduction and IVF group, 10.5% (16) as compared to the IVF only group 2.6% (4) (P = 0.009). Miscarriage rates and gonadotropin dose used for IVF stimulation did not differ between groups. Two subgroup analyses were performed. The first compared women with PCOS in the two randomized groups, and the second compared women in the weight reduction group reaching BMI <= 25 kg/m(2) or reaching a weight loss of at least five BMI units to the IVF only group. No statistical differences in live birth rates between the groups in either subgroup analysis were found. LIMITATIONS, REASON FOR CAUTION: The study was not powered to detect a small increase in live births due to weight reduction and was not blinded for the patients or physician. Further, the intervention group had a longer time to achieve a spontaneous pregnancy, but were therefore slightly older than the control group at IVF. The study only included women with a BMI lower than 35 kg/m(2). WIDER IMPLICATIONS OF THE FINDINGS: The study suggests that weight loss for obese women (BMI: 30-34.9 kg/m(2)) may not rectify the outcome in IVF cycles, although a significant higher number of spontaneous conceptions occurred in the weight loss group. Also, the study suggests that intensive weight reduction with LCD treatment does not negatively affects the results.