Researchers study effect of Mediterranean diet on pregnancy outcomes

A Mediterranean-style diet in pregnancy does not reduce the risk of overall adverse maternal and offspring complications, but may reduce weight gain during pregnancy and the risk of gestational diabetes, according to a new study published this week in PLOS Medicine by Shakila Thangaratinam of Queen Mary University of London, UK, and colleagues.

A Mediterranean-style diet is defined by high intake of nuts, extra virgin olive oil, fruits, vegetables, non-refined grains and legumes; moderate intake of fish; low intake of red and processed meat; and avoidance of sugary drinks, fast food, and food rich in animal fat. In the new ESTEEM study, researchers randomized 1252 pregnant women with metabolic risk factors from five inner city UK hospitals. 627 were assigned to a Mediterranean-style diet, and were given mixed nuts and olive oil, and participated in three face-to-face sessions as well as follow up phone calls to reinforce dietary goals. 625 women were assigned to a control group and received dietary advice per UK national guidelines.

Women in the intervention group consumed significantly more nuts (adjusted OR 6.8, 95% CI 4.3-10.6), more extra virgin olive oil (aOR 32.2, 95% CI 16.0-64.6), increased their consumption of fish, white meat and pulses, and decreased their consumption of red meat, butter, margarine and cream. There was no significant reduction in the odds of overall maternal or offspring outcomes with the Mediterranean-style diet. However, there was a reduction in the odds of gestational diabetes by 35% (aOR 0.65, 95% CI 0.47-0.91), and this benefit was consistently observed when ESTEEM data were combined with those of similar trials (OR 0.67, 95% CI 0.53-0.84). Women in the ESTEEM intervention group gained, on average, 6.8 kilograms in weight compared to 8.3 kilograms gained in the control group.

"Future studies should assess the effect of in utero exposure to Mediterranean-style diet, particularly to nuts and olive oil, on childhood obesity, allergy and asthma, and on mother's future risk of type 2 diabetes," the authors say.