In a clinical trial in The American Journal of Clinical Nutrition, 279 pregnant women who were classified as having overweight or obesity before pregnancy were randomly assigned to follow one of two programs: a higher-protein, lower-glycemic diet (25%–28% of energy from protein and glycemic index ≤ 55) or a moderate-protein, moderate-glycemic diet (15%–18% of energy from protein and a glycemic index around 60).
The results showed that increasing protein intake and improving carbohydrate quality during the last two trimesters of pregnancy reduced gestational weight gain and, more importantly, risk of complications and deliveries by C-section. Birth weight and incidence of miscarriages did not differ between groups.
A separate investigation in the same journal reported that when moms-to-be adhered to a higher-quality diet during pregnancy—as assessed with pregnancy-appropriate versions of the Mediterranean Diet Score and Alternate Healthy Eating Index—infants had improved visual sensory processing. And when children were a few years older, they had higher intelligence and better executive functioning, which includes working memory and flexible thinking. Indeed, eating for two should not be taken lightly.