Abstract
BACKGROUND Prepregnancy overweight and excessive gestational weight gain (GWG) increase the risk of complications and offspring obesity. OBJECTIVES We aimed to investigate the effect of a high-protein low-glycemic index (HPLGI) diet on GWG, birth weight, and risk of gestational complications in pregnant women with obesity. METHODS A total of 279 women with prepregnancy overweight or obesity (BMI: 28-45 kg/m2), between 18 and 45 y old, and in their late first trimester with singleton pregnancies, were randomly assigned to 1 of 2 ad libitum diets: a high-protein low-glycemic index diet (HPLGI 25%-28% of energy from protein and glycemic index ≤ 55) and a moderate-protein moderate-glycemic index diet (MPMGI 15%-18% of energy from protein and glycemic index ∼60). Diets were consumed from gestational week 15 and throughout pregnancy. Participants received dietary guidance by a clinical dietician 9 times to facilitate adherence. RESULTS Out of 141 and 138 women randomly assigned to the HPLGI and MPMGI diets, 105 and 104 completed the intervention, respectively (75%). In the available case analyses, GWG was 6.8 ± 1.3 kg among women assigned the HPLGI diet and this was significantly lower, by -1.7 kg (95% CI: -2.8, -0.5 kg; P = 0.004), than the GWG of 8.5 ± 1.3 kg among women assigned the MPMGI diet. There were no significant differences between diets on major neonatal outcomes (birth weight and other anthropometric measures). The incidence of composite pregnancy complications was lower for the HPLGI than for the MPMGI diet (35.4% compared with 53.7%, respectively; P = 0.009), including cesarean delivery (15.4% compared with 28.8%, respectively; P = 0.03). There were no reported maternal, fetal, or neonatal deaths. Incidence of miscarriages (1%-2%) did not differ between groups. CONCLUSIONS A moderate increase in dietary protein in conjunction with a reduction in glycemic index during the last 2 trimesters of pregnancy reduced GWG and limited complications and cesarean deliveries among women with overweight or obesity.
