Introduction: Large observational studies have shown that obstetric and perinatal outcomes are negatively affected in obese women. In contrast, a recent Dutch randomized trial of infertile women and lifestyle weight intervention found no difference between the weight intervention group and the control group in obstetric or neonatal outcomes. We have recently published a large Nordic randomized trial where obese women scheduled for in vitro fertilization (IVF) treatment went through an intensive weight intervention treatment before IVF. No significant effect on live birth rate was found, despite large weight loss in the intervention group. The present study was conducted primarily to find out the effect of weight intervention in obese women scheduled for IVF on mean birthweight and mean deviation from expected birthweight, and secondarily the effect on other perinatal and maternal outcomes.
Material and methods: A secondary analysis of a prospective, randomized controlled trial performed between 2010 and 2016 in the Nordic countries was performed. In all, 317 women were randomized either to weight reduction and IVF treatment (n = 160) or IVF only (n = 157) and the primary end-point was live birth. From this study, all births were analyzed for perinatal and maternal outcomes. Nine infertility clinics participated, including women < 38 years of age planning for IVF, and having a body mass index ≥ 30 and < 35 kg/m2 . Data concerning perinatal and maternal outcomes were gathered from maternal health-care and delivery records for mother and child. All analyses were performed on singletons only.
Results: There were 87 live births, 45 singletons in the intervention group and 41 singletons and one twin birth in the control group. The maternal characteristics for the women having a live birth were comparable in the two groups. The primary outcomes, mean birthweight, in the weight intervention and IVF group and the IVF only group were; 3486 g (standard deviation [SD] 523) vs 3584 g (SD 509) (P = 0.46), mean difference -98.6 g (95% confidence interval [CI] -320.3 to 123.2); deviation from expected birthweight 0.25% (SD 10.4) vs 0.87% (SD 12.9), mean difference 1.1% (95% CI -6.1 to 3.9). The estimates of the secondary perinatal and maternal outcomes in the 2 groups were: preterm birth < 37 weeks 2 (4.4%) vs 1 (2.4%) (odds ratio [OR] 1.95; 95% CI 0.17-22.36), small-for-gestational-age 0 (0%) vs 1 (2.4%), mean gestational age (days) 278 vs 280 (P = 0.95), preeclampsia 5 (11.1%) vs 4 (9.8%) (OR 1.19; 95% CI 0.30-4.76), cesarean section 13 (28.9%) vs 10 (24.4%) (OR 1.14; 95% CI 0.45-2.94).
Conclusions: The outcomes in both groups were generally good. There are no indications that weight intervention in this setting, in infertile women with obesity WHO class 1 undergoing IVF, has a negative impact on mean birthweight and deviation from expected birthweight. However, the data are not sufficiently robust to draw firm conclusions concerning other outcomes.
Keywords: in vitro fertilization; infant birthweight; infertility; maternal outcome; obesity; perinatal outcome; weight reduction.
© 2019 Nordic Federation of Societies of Obstetrics and Gynecology.