New Study Suggests that a Mediterranean Diet Could Reduce the Risk of Complications

A new study from the US has found that adhering to a Mediterranean diet around the time of conception may help mothers-to-be reduce their risk of complications later on in their pregnancy.

While the study’s author stresses that further research is needed to explore the link between the diet and healthier pregnancies, the findings do provide an encouraging insight into how beneficial certain foods may be when eaten as part of a pregnancy diet.

What is a Mediterranean diet?

The Mediterranean diet is often championed by nutritionists and doctors as one of the most beneficial diets around, taking the top spot for the sixth consecutive year in U.S. News & World Report’s 2023 list of best overall diets. But what foods are involved, and why are they so beneficial?

As the name suggests, the Mediterranean diet contains the foods the inhabitants of Mediterranean countries generally eat. It is predominantly plant-based, consisting of fresh fruits, vegetables, nuts, legumes, and whole grains. Sources of protein include fish, poultry, and eggs, and fat should come mainly from unsaturated sources, such as olive oil. Refined sugars, red meat, and alcohol should be consumed sparingly, as should all highly processed foods.

Since the Mediterranean diet is nutrient-dense, medical experts believe it has a range of health benefits for everyone. The NHS notes that the Mediterranean diet reduces the risk of cardiovascular disease, diabetes, dementia, certain cancers, and high blood pressure.

The study

The aim of this recent study, published in JAMA Network in December 2022, was to see if a Mediterranean diet could help pregnant women prevent adverse outcomes.

Researchers from the Cedars-Sinai Hospital in Los Angeles enrolled a cohort of 7,798 pregnant women, all in their first trimester, and asked them to complete a food frequency questionnaire that examined their diet in the prior three months. The participants were scored from 0-9 based on their consumption of nine components – vegetables, fruits, nuts, whole grains, legumes, fish, monounsaturated-to-saturated fat ratio, red and processed meats, and alcohol. The higher their score, the greater their adherence to the Mediterranean diet.

The findings

After collating the data, the researchers then examined the correlation between the scores and the development of an adverse pregnancy outcome, which they defined as one of the following: pre-eclampsia (defined by high blood pressure and protein in urine), eclampsia (a severe complication of pre-eclampsia), gestational hypertension, gestational diabetes, preterm birth (birth before 37 weeks), delivery of a small-for-gestational-age infant, or stillbirth.

The results showed that women with higher scores had:

• a 21% lower chance of developing any adverse pregnancy outcome.
• a 28% lower risk of pre-eclampsia.
• a 38% lower risk of gestational diabetes.

The study’s author, Dr Natalie Bello, MPH, said that while the diet benefitted women of all races, ethnicities, and BMIs equally, the result suggested the diet may be more beneficial for women over 35.

Christine Albert, chair of the Department of Cardiology at the hospital, said, “These findings add to the growing body of evidence demonstrating that the Mediterranean-style diet may play an important role in preserving the health of women across the lifespan, including during pregnancy.”

While the results are encouraging, it’s important to note a few of the study’s limitations. As the study relied on self-reported data, the adherence scores may not have been entirely accurate. Some participants also had access to certain prenatal care, which would have affected their outcomes, and because the study was observational, it could not establish causality.

Dr Bello said that further long-term studies were needed to better understand the link between a Mediterranean diet and the reduced risk of pregnancy complications.

Potential issues with a Mediterranean diet during pregnancy

The Mediterranean diet promotes a high intake of healthy fruit and vegetables, which are great for overall wellbeing, but not every component of the diet may be suitable for pregnant women. Certain types of fish, for instance, are not safe for pregnant women to eat. This is because they contain mercury and other pollutants that can harm the unborn baby. The NHS recommends that mums-to-be avoid the following fish because of their mercury content:

• Swordfish
• Raw shellfish
• Shark
• Marlin

Oily fish – such as salmon, trout, mackerel, and herring – should be limited to only two portions a week. Tuna should be eaten in strict moderation, too (no more than two medium-sized cans of tuna a week).

If you would like more information and guidance on your diet during pregnancy, speak to a healthcare professional.