Mediterranean Diet During Pregnancy and Childhood Respiratory and Atopic Outcomes: Birth Cohort Study

To assess whether adherence to a Mediterranean diet in pregnancy was associated with a reduced risk of asthma and other atopic outcomes and a higher lung function test in school-aged offspring.

The study used a population birth cohort out of Avon, United Kingdom that included 14 541 white pregnant women. Women had a delivery date between April 1, 1991, and December 31, 1992. Out of this cohort, 8907 mother-child pairs were analyzed to include only women of singleton or twin deliveries, with information on their diet during pregnancy and at least one of the outcomes of interest in their offspring.

Data on maternal diet were collected by a food frequency questionnaire at 32 weeks' gestation. Numeric values were assigned to diets based on a Mediterranean diet score, ranging from 0–7, with higher values attributing to a higher adherence to a Mediterranean diet. Children ages 7–8 years were defined to have asthma if a doctor gave a diagnosis of asthma and parents endorsed wheezing or whistling in the past 12 months. Wheezing or hay fever was defined by answering yes to “Has you child had any of the following in the past 12 months: wheezing with whistling; eczema; hay fever?” Atopy was defined as a positive skin prick test. Lung function was determined by spirometry. Statistical analysis involved comparing mother-child variables with women scoring a Mediterranean diet score ≥4 to those ≤3, using a t test and χ² test. Logistic regression, multinomial logistic regression, and linear regression were used between maternal Mediterranean diet in pregnancy and binary, categorical, and continuous outcomes. Confounding factors were removed to further categorize data, and stratification was specifically made to explore maternal effects of smoking with a Mediterranean diet.

After controlling for confounders, maternal Mediterranean diet was not associated with asthma, wheeze, eczema, hay fever, or atopy. However, a positive association was found for childhood lung function (FEV1 and FEF_{25% to 75%}) in children ages 8-9 whose mothers had a higher Mediterranean diet score (difference in age, height, and sex-adjusted SD units 0.06, 95% CI 0.01–0.12; P value .03). Additionally, a Mediterranean maternal diet was positively associated with FEF_{25% to 75%} among non-smoker or passive smoker mothers; when this negative association was stratified with maternal smokers, no evidence of attenuation of association was discovered.

There is weak evidence that greater adherence to a Mediterranean diet in pregnancy is associated with improved lung function in children, but no association with asthma or other atopic outcomes.

This is the first study to assess childhood lung function in association with a Mediterranean diet. Despite findings that there is a weak association with a Mediterranean diet in pregnancy and childhood lung function, there was no association with asthma or other allergic disease. Based on this study, early intervention with a Mediterranean diet in pregnancy may not prevent the development of allergic diseases including asthma. Prospective studies are needed to confirm these findings, particularly studies evaluating maternal diet during pregnancy and the diet of the infant as their immune system continues to develop, as a combination of both is more likely to play a role in allergic disease development.