A healthy prenatal dietary pattern that includes fruits, vegetables, nuts, whole grains, and fish, is recommended so as to reduce risk of autism, according to a new study.

The study published on July 18 in JAMA Network Open, a prominent medical journal, investigates the impact of maternal dietary habits during pregnancy on the risk of childhood autism. Experts indicated that maternal dietary patterns during pregnancy significantly influence fetal development.

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However, the impact of dietary habits on the risk of autism has not been thoroughly evaluated, as most existing studies focused on specific nutrients or foods, such as vitamin D, multivitamins, folic acid, or fish intake.

The current study obtained data from the Norwegian Mother, Father, and Child Cohort Study (MoBa) and Avon Longitudinal Study of Parents and Children (ALSPAC) conducted in Norway and Southwest England, respectively. Study participants were recruited between 2002-2008 and 1990-1992 for the MoBa and ALSPAC cohorts, which encompassed 84,548 and 11,760 pregnant women.

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All study participants had singleton pregnancies (pregnancy with just one baby at a time), and their food habits were assessed using food frequency questionnaires.

The children of these mothers were monitored until they reached at least eight years of age. In the MoBa cohort, assessed outcomes included a diagnosis of autism, impaired social communication, and restrictive and repetitive behaviors at three years of age.

For the ALSPAC cohort, only social communication difficulties were evaluated at eight years of age.

The MoBa study applied the Social Communication Questionnaire (SCQ) for autism-associated social communication difficulties (SCQ-SOC) and restrictive and repetitive behaviors (SCQ-RRB).

For ALSPAC, the Social and Communication Disorders Checklist (SCDC), which measures social and communication skills, was used. Mothers were classified according to their adherence to a healthy diet pattern into low, medium, and high adherence groups.

Healthy prenatal dietary pattern

A healthy prenatal dietary pattern (HPDP) was defined as one that includes fruits, vegetables, nuts, whole grains, and fish. Lower adherence to HPDP was identified when foods with higher fat and refined sugar content were reported.

Mothers with high adherence to a healthy diet had children who were at a reduced risk of autism as compared to those with low adherence.

Overall, mothers who followed a healthy diet during pregnancy had a higher mean level of education, were older, more likely to be nonsmokers, and used prenatal vitamins during pregnancy.

In the MoBa cohort, follow-up at three years showed a 24 per cent reduction in the risk of social communication difficulties among children born to the high adherence cohort compared to those born to the lowest adherence cohort.

Females had a higher reduction in risk than males. Particularly, girls often develop communication skills earlier than boys.

For the ALSPAC cohort, follow-up at eight years showed a similar reduction in risk.

Researchers found that autism-associated behavioral traits were not significantly linked with maternal dietary habits during pregnancy. They stressed that the observation may be due to several reasons such as communication difficulties or repetitive behaviors may be detected in children who do not have autism, especially in younger children.

The risk of having a child diagnosed with autism or who exhibits difficulties with social communication was lower among mothers who consumed a healthy prenatal diet.