Efficacy of Mediterranean Diet in pregnancy: A systematic review and meta-analysis featured in the Italian National Guidelines "La Dieta Mediterranea".

Maternal nutritional status and dietary patterns represent key determinants of pregnancy outcomes and long-term health of the offspring, through metabolic, epigenetic, and developmental programming mechanisms. Mediterranean Diet (MD) has been widely acknowledged as a model of healthy eating, with anti-inflammatory and cardiometabolic benefits, and evidence on the impact of MD during pregnancy on maternal/infant outcomes is growing. The present systematic review and meta-analysis evaluates the association between adherence to MD during pregnancy and maternal and neonatal health outcomes. This review was conducted in accordance with PRISMA 2020 and MOOSE guidelines. A comprehensive search of PubMed/MEDLINE, Scopus, Embase, and Cochrane Library was performed up to February 28, 2024. Study quality was assessed using the Newcastle-Ottawa Scale, and the certainty of evidence was evaluated with the NUTRIGRADE approach. Pooled effect sizes were computed using a random-effects model and expressed as risk ratios (RR), hazard ratios (HR), or odds ratios (OR), as appropriate. Thirty-three studies (19 RCTs and 14 observational; >180 000 pregnant women) were included. Higher MD adherence was associated with lower risk of gestational diabetes mellitus (cohorts: OR 0.93, 95% CI 0.91-0.96; RCTs: RR 0.74, 95% CI 0.63-0.88), preterm delivery (cohorts: OR 0.96, 95% CI 0.92-0.99; RCTs: RR 0.45, 95% CI 0.05-0.84), low neonatal weight (cohorts: OR 0.96, 95% CI 0.91-1.00; RCTs: RR 0.61, 95% CI 0.42-0.88) and fetal growth alterations (RR 0.93, 95% CI 0.87-0.995). Evidence for pre-eclampsia was inconsistent, with significant associations in cohorts but not in RCTs. No significant effects were found for caesarean section, fetal death, neonatal asthma, or childhood obesity. NUTRIGRADE indicated moderate-to-high certainty for gestational diabetes, preterm delivery and low neonatal weight, and low certainty for other outcomes. Adherence to MD during pregnancy is associated with reduced risk of gestational diabetes, preterm birth and abnormal fetal growth. Given its safety and broader cardiometabolic benefits, the MD represents a suitable dietary pattern in pregnancy, although further high-quality trials with diverse populations and standardized MD metrics are warranted.