The Effect of Lower Carbohydrate and Lower Glycemic Index Diets in Maternal and Neonatal Outcomes among Pregnant Women: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Author(s): Greg J. Marchand, MD, FACS, FACOG*, Daniela Gonzalez Herrera, BS, Mckenna Robinson, BS, Emily Kline, BS, Sarah Mera, BS, Michelle Koshaba, BS, Nidhi Pulicherla, BA, Brooklynn O'Connell BS, Fatma Ibrahim, MD, Katelyn Sainz, MD

Objective: To evaluate the effects of low-carbohydrate (low-CHO), low-glycemicindex (low-GI), and low-glycemic-load (low-GL) diets on maternal and neonatal outcomes in pregnant women.

Methods: Systematic review and meta-analysis of randomized controlled trials (RCTs). Six databases were searched from inception to 1 January 2024. Included RCTs compared low-CHO with higher-CHO diets or low-GI/GL with higher-GI/ GL diets in pregnancy, using authors’ definitions. Risk of bias was assessed with Cochrane RoB 2 tool; analyses were performed in Review Manager 5.3.5.

Results: Twenty-four RCTs (n=3795 women) were included: 5 examined low- CHO diets and 19 examined low-GI or low-GL diets. Low-CHO diets showed no significant benefits for maternal or neonatal outcomes. Low-GI/GL diets significantly reduced postprandial glucose (SMD −0.40, 95% CI −0.53 to −0.28), gestational weight gain (SMD −0.14, 95% CI −0.21 to −0.07), excess weight gain (RR 0.79, 95% CI 0.68–0.90), large-for-gestational-age infants (RR 0.70, 95% CI 0.50–0.98), and preterm delivery (RR 0.55, 95% CI 0.40–0.77). They also improved lipid profiles (higher HDL, lower total cholesterol and triglycerides). No significant effects were seen on fasting glucose, HbA1c, insulin requirement, LDL, gestational age at delivery, cesarean section rate, small-for-gestational-age infants, birth weight, or newborn length.

Conclusion: In pregnancy, low-GI or low-GL diets are associated with modest improvements in maternal glycemia, weight gain, lipid profile, and selected neonatal outcomes (fewer LGA infants and preterm births). Evidence for low-CHO diets remains limited, with no clear benefits demonstrated in the small number of available RCTs.