Pregnancy-adapted Mediterranean diet improves maternal health, study finds

By Vijay Kumar MalesuReviewed by Susha Cheriyedath, M.Sc.Jun 4 2024

In a recent study published in The American Journal of Clinical Nutrition, a group of researchers validated the 17-item pregnancy-adapted Mediterranean diet score (preg-MEDAS) within the Improving Mothers for a better PrenAtal Care Trial BarCeloNa (IMPACT BCN) trial and analyzed its association with maternal dietary and cardiometabolic changes after three months of intervention.

Study: Validation of a pregnancy-adapted Mediterranean diet Adherence Screener (preg-MEDAS): A validation study nested in the IMPACT BCN trial. Image Credit: monticello / Shutterstock

Background

Maternal diet is crucial for fetal development and can impact pregnancy complications, adverse outcomes, and long-term chronic diseases. The Mediterranean Diet (MedDiet) is globally recognized for its health benefits, including during pregnancy, positively influencing maternal and offspring health. In the IMPACT BCN trial, a pregnancy-adapted MedDiet significantly reduced the incidence of small for gestational age (SGA) newborns and other perinatal complications. Further research is needed to explore the long-term impact of the pregnancy-adapted MedDiet on maternal and fetal health outcomes.

About the study 

The present study was conducted at BCNatal, Spain, involving 1,221 pregnant women at high risk for SGA newborns. At 19-23 weeks gestation, participants were randomly assigned to one of three groups: a MedDiet intervention, a mindfulness-based stress reduction program, or usual care. Recruitment occurred from February 2017 to October 2019, with follow-up until delivery (March 2020) and additional postnatal visits at 1-3 months, 12 months, 24 months, and 6 years. The study was approved by the Institutional Review Board of the Hospital Clínic of Barcelona (HCB-2016-0830), and all participants provided written informed consent.

For this analysis, 812 participants were included after excluding those with incomplete dietary data or other disqualifying factors. Dietary data were collected using the preg-MEDAS and a 151-item semi-quantitative food frequency questionnaire (FFQ). The preg-MEDAS, adapted from the MEDAS to suit pregnancy, scored compliance on a 0-17 scale. Food intake data from the FFQ were converted into energy and nutrient intake.

Maternal weight, height, body mass index (BMI), and blood pressure were measured at recruitment and final visit. The validity of the preg-MEDAS was assessed by comparing it with the FFQ using cross-classification, kappa statistic, Pearson correlation, and Bland-Altman methods. Statistical analyses were performed using SPSS, with significance set at P < 0.05.

Study results

In the study, participants with higher adherence to the MedDiet were older and had lower preconceptional body weight and BMI. Women with the highest adherence also showed a higher percentage of nulliparity and use of assisted reproductive technologies (both at 40.2%). 

Cross-classification was employed to assess absolute agreement and correlation between preg-MEDAS and FFQ. Agreement ranged from 41% for processed meat consumption to 94% for butter, margarine, or cream consumption, with an average agreement of 79.3%. Kappa statistics indicated slight to almost perfect agreement, with a mean kappa of 0.61, suggesting substantial agreement. The Pearson (0.76) and intraclass correlation coefficients (ICC = 0.75) indicated strong correlations between preg-MEDAS and FFQ scores. The mean preg-MEDAS score was 7.73 ± 2.52, slightly overestimating the FFQ score by 0.55 points. The β-coefficient (0.52) suggested discrepancies were more apparent at higher scores. The Bland-Altman plot indicated minimal bias.

After three months of intervention, participants who improved their preg-MEDAS score by ≥2 points had increased daily energy intake and higher consumption of vegetables, fruits, legumes, whole grains, fish, fatty fish, nuts, extra virgin olive oil, and dairy products, while consuming less refined cereals and sweets. These results are expressed as non-standardized β-coefficients and 95% CIs, adjusted for various factors, including intervention arm, age, education, and pre-pregnancy BMI.

A 2-point increase in preg-MEDAS score was inversely associated with mean and systolic blood pressure in both minimally and fully adjusted models. Specifically, mean blood pressure decreased by 0.51 mmHg and systolic blood pressure by 0.87 mmHg. No significant associations were found between changes in preg-MEDAS score and body weight gain, ferritin, albumin, cholesterol,  BMI change, diastolic blood pressure, or levels of hemoglobin, triglycerides, transferrin, HbA1c, vitamin B12, and folic acid.

No significant associations were observed regarding neonatal outcomes between a 2-point change in preg-MEDAS score and birthweight, birthweight percentile, or gestational age. 

Conclusions 

To summarize, modifications from the original MEDAS included removing wine and sugar items, adjusting meat and fruit consumption questions, and adding items on fatty fish and dairy. Strong correlations between preg-MEDAS and FFQ indicate effectiveness, with substantial agreement across most food items. A three-month dietary intervention increased key MedDiet food intake and improved blood pressure. These findings suggest that while improvements in preg-MEDAS score are associated with better maternal cardiometabolic health, they do not significantly impact neonatal birth outcomes.