But 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.
Having a Mediterranean-style diet led to a 35 per cent lower risk of developing diabetes in pregnancy, according to a clinical trial led by Queen Mary University of London and the University of Warwick. Published in the journal PLOS Medicine and funded by Barts Charity, it also found women on the diet gained on average 1.25kg 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 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.