Eating a Mediterranean-style diet during pregnancy has the potential to reduce weight gain and the risk of gestational diabetes, researchers say.
However the diet, which includes a high intake of nuts, extra virgin olive oil, fruit, vegetables, and moderate to high consumption of fish, does not reduce the overall risk of complications in the mother and baby.
According to a clinical trial led by Queen Mary University of London and the University of Warwick, having a Mediterranean-style diet led to a 35% lower risk of developing diabetes in pregnancy.
Published in the journal PLOS Medicine and funded by Barts Charity, it also found women on the diet gained on average 1.25 kg less weight, compared with those who received routine antenatal care.
A Mediterranean-style diet could be an effective intervention for women who enter pregnancy with pre-existing obesity, chronic hypertension or raised lipid levels, the study suggests.
Professor Shakila Thangaratinam, from Queen Mary University of London, said: “This is the first study to show that pregnant women at high risk of complications may benefit from a Mediterranean-style diet to reduce their weight gain and risk of gestational diabetes.
“Implementing this diet seems to be effective and acceptable to women.
“Current national dietary guidelines do not include the key components of the Mediterranean-style diet in their recommendations.
“Women who are at risk of gestational diabetes should be encouraged to take action early on in pregnancy, by consuming more nuts, olive oil, fruit and unrefined grains, while reducing their intake of animal fats and sugar.”
One in four mothers enter pregnancy with pre-existing obesity, chronic hypertension or raised lipid levels which can lead to pregnancy complications.
A Mediterranean-style diet, rich in unsaturated fatty acids, reduces the incidence of cardiovascular diseases in the non-pregnant population.
In pregnancy, such a diet has the potential to improve maternal and offspring outcomes, but has not been widely evaluated until now.
The ESTEEM study involved 1,252 women at five UK maternity units, four in London, and one in Birmingham.
Multi-ethnic inner-city pregnant women with metabolic risk factors were randomised to either receive routine antenatal care or a Mediterranean-style diet in addition to their antenatal care.
The diet included a high intake of nuts, extra virgin olive oil, fruit, vegetables, non-refined grains and legumes, moderate to high consumption of fish, and a small to moderate intake of poultry and dairy products.
It also featured a low intake of red meat and processed meat, and avoidance of sugary drinks, fast food, and food rich in animal fat.
To promote their intake in pregnancy, participants on the Mediterranean-style diet were provided with 30g a day of complementary mixed nuts, and 0.5 litres of extra virgin olive oil a week as the main source of cooking fat.
Participants also received individualised dietary advice at 18, 20 and 28 weeks’ gestation.
An overall better quality of life was reported by the women in the Mediterranean-style diet group.
They further reported reduced bloatedness in pregnancy, but there was no effect on other symptoms such as nausea, vomiting or indigestion.
When combined with data from a Spanish study involving 874 pregnant women on a Mediterranean diet, the team observed a similarly large reduction in gestational diabetes, 33%, but no effect on other outcomes.