A Greater Adherence to the Mediterranean Diet Supplemented with Extra Virgin Olive Oil and Nuts During Pregnancy Is Associated with Improved Offspring Health at Six Years of Age

<b>Background/Objectives:</b> Children's health may be influenced by maternal eating habits during pregnancy. A Mediterranean diet (MedDiet)-based pattern has been associated with benefits in infectious disease and allergies in children. <b>Methods:</b> From a total 2228 pregnant women evaluated between 2015 and 2017 in the St. Carlos cohort, 1292 women belonging to the intervention group (IG) undertook a MedDiet supplemented with extra virgin olive oil (EVOO) and nuts from early on in pregnancy. The control group (CG) consisted of 516 pregnant women who were advised to follow a fat-restricted MedDiet. The modified 12-point Mediterranean diet adherence screener (MEDAS) was applied. A total of 1808 (81.2%) children were analyzed at 6 years postpartum. All women from both groups received the same postpartum nutritional recommendations as the IG had during pregnancy. <b>Results:</b> Children from the IG showed lower rates of bronchiolitis and atopic eczema compared to the CG. Children whose mother's MEDAS score was ≥6 at 24-28 GW vs. MEDAS scores < 6 presented lower rates of bronchiolitis [222/695 (28.8%) vs. 441/1113 (39.6%); <i>p</i> = 0.022] and atopic eczema [311/695 (39.0%) vs. 564/1113 (50.7%); <i>p</i> = 0.039]. The offspring of mothers with MEDAS scores ≥ 8 (<i>n</i> = 176) vs. MEDAS scores ≤ 3 (<i>n</i> = 564) showed a lower relative risk (RR) (95% CI) for developing bronchiolitis [0.75 (0.58-0.97)] and atopic eczema [0.82 (0.69-0.98)], with both having a <i>p</i> < 0.001 trend. <b>Conclusions:</b> A higher adherence to a MedDiet supplemented with EVOO and nuts during pregnancy is associated with health benefits in offspring at 6 years of age.