The Mediterranean diet (MD) is universally recognized as a healthy and effective aid to managing body weight and overall health. A recent study published in Advances in Nutrition explores available evidence on how consuming the MD during pregnancy affects perinatal health.
Study: Association between the maternal Mediterranean diet and perinatal outcomes: a systematic review and meta-analysis. Image Credit: NDAB Creativity / Shutterstock.com
The health benefits of MD
The MD is associated with a high consumption of whole grains, vegetables, legumes, nuts, fish, olive oil, and fruits. Rich in antioxidants and anti-inflammatory compounds, the MD has been shown to prevent and treat cardiovascular disease (CVD), metabolic disease, autoimmune conditions, poor mental health, and cancers. The MD also reduces overall mortality rates and promotes a healthy aging pattern.
The maternal diet can significantly impact the health of both the mother and fetus during pregnancy and thereafter. Thus, an adequate and high-quality maternal diet is essential for fetal growth and metabolic and physiological homeostasis.
Many studies have investigated the importance of dietary and nutritional status during pregnancy, which can help prevent conditions like gestational diabetes mellitus (GDM), preterm delivery, and perinatal illness.
Previous studies have indicated an improvement in metabolic health when following the MD; however, there is a lack of meta-analyses on this topic. Additionally, not all available randomized controlled trials (RCTs) have been included.
The combined use of interventional, observational, prospective, and cross-sectional studies has increased concerns regarding the potential impact of recall bias and reverse causality. As a result, there is limited evidence on the association of the MD with metabolic health in pregnancy, which motivated the current study.
Study findings
In the current study, researchers reviewed 23 articles, including five RCTs and 18 cohort studies, in their systematic meta-analysis. These studies comprised 107,355 individuals from 10 different countries, including the United Kingdom, Spain, China, the United States, Greece, Norway, Denmark, Australia, and the Netherlands. Notably, almost every study relied on the food frequency questionnaire (FFQ) to obtain dietary intake information.
The five RCTs reported a significantly reduced risk of GDM and small for gestational age (SGA) babies. Similar results were observed in the cohort studies, in which the MD was associated with a reduced risk of GDM, pregnancy-induced hypertension, pre-eclampsia, preterm delivery, low birth weight (LBW), and intrauterine growth restriction (IUGR) was observed, along with an increase in gestational age at delivery. A significant correlation was also observed between maternal MD and the incidence of preterm delivery.
The greatest uniformity was observed for the association between MD adherence and pregnancy-linked hypertension, preterm delivery, and LBW. In two studies that accounted for confounding factors, the likelihood of pregnancy-linked hypertension was reduced by 30% among those on the MD. This was also observed in non-Mediterranean countries, but not when only Mediterranean countries were included.
Similarly, the risk of preterm delivery among mothers who followed the MD was significantly reduced after considering potential confounding factors. However, the other parameters failed to show significant associations after such an adjustment.
The pooled results demonstrate that following the MD during pregnancy reduces the risk of GDM and SGA in intervention studies. Cohort studies show that the MD produces positive effects in almost all outcomes, such as better metabolic health, reduced risk of pregnancy hypertension, increased birth weight, and higher gestational age at delivery.
The underlying mechanisms responsible for the perinatal benefits of the MD may include the high antioxidant and anti-inflammatory content of this diet. Importantly, low-carbohydrate plant-based nutrition helps achieve satiety sooner, thereby supporting healthy weight management, particularly during pregnancy. By reducing systemic inflammation, this may help reduce the risk of preterm labor and high blood pressure during pregnancy, as well as of GDM.
Conclusions
Our meta-analysis solely focuses on robust evidence from RCTs and cohort studies, providing a comprehensive perspective on the potential associations between the maternal MD and both maternal and offspring outcomes.”
Future studies need to include different types of evidence to determine the role of other confounding factors not considered in the studies included in the current meta-analysis. Larger study samples are also crucial to ensure the power to detect these effects and guide clinical recommendations for diet during pregnancy.
Journal reference:
- Xu, J., Wang, H., Bian, J., et al. (2024). Association between the maternal mediterranean diet and perinatal outcomes: a systematic review and meta-analysis. Advances in Nutrition 15(2). doi:10.1016/j.advnut.2023.100159.
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