AM J OBST GYNEC MFM

Background: Maternal suboptimal nutrition and high stress levels are associated with an altered fetal cardiovascular function.

Objective: To study the effect of structured maternal lifestyle interventions based on a Mediterranean diet or Mindfulness-Based Stress Reduction intervention during pregnancy on fetal cardiac function.

Study design: This was a secondary analysis of the IMPACT BCN (Improving Mothers for a better PrenAtal Care Trial BarCeloNa) randomized clinical trial, which was conducted at a university hospital in Barcelona, Spain, from February 2017 to March 2020. A total of 1,221 singleton pregnancies (19 to 23 weeks' gestation) with high risk of delivering small-for-gestational-age newborns were randomly allocated into 3 groups in a 1:1:1 ratio: a Mediterranean diet intervention, a stress reduction program, or usual care. Participants in the Mediterranean diet group received monthly individual and group educational sessions and free provision of extra virgin olive oil and walnuts. Those in the stress reduction group underwent an 8-week mindfulness based stress reduction program adapted for pregnancy. Individuals in the usual care group received pregnancy care per institutional protocols. Fetal cardiac function assessed by cord blood N-terminal pro B-type natriuretic peptide (NT-proBNP) and fetal echocardiography. NT-proBNP was measured in cord blood collected at delivery and considered high if above 90th centile. Fetal echocardiography was performed at 33-34 weeks' gestation. Data were analyzed from January to July 2024.

Results: Fetal echocardiography and cord blood NT-proBNP were obtained in 990 and 746 pregnancies respectively. While fetuses from the Stress Reduction group showed similar fetal cardiac results, the proportion of fetuses with high cord blood NT-proBNP concentrations was significantly lower in Mediterranean diet (6.4% vs. 12%, p=0.03) compared to usual care group. Additionally, fetuses whose mothers followed Mediterranean diet showed higher right ventricular fractional area change (mean (standard deviation) 30.4 (8.3) % vs. 28.1 (8.9) %, p=0.03) and thinner myocardial wall (mean (standard deviation) 2.95 (0.55) mm vs. 3.16 (0.58) mm, p=0.006) compared to usual care.

Conclusion: Promotion of maternal Mediterranean diet intervention during pregnancy seems to be associated with a less overloaded and more efficient fetal heart. Future research is warranted to elucidate the mechanism(s) underlying these findings.