During pregnancy, the ratio between Omega-6 and Omega-3 intake influences the neurodevelopment of the fetus

Pregnancy: the Omega-3 to Omega-6 ratio is essential for healthy brain growth in the baby

A diet rich in Omega-6 and poor in Omega-3 during pregnancy is associated with abnormalities in fetal brain development. An inadequate intake of polyunsaturated fatty acids by the mother thus increases the risk for the newborn to develop cognitive and behavioral deficiencies.

This emerges from the EDEN Mother-Child Study, a French study carried out by researchers from INSERM (Institut National de la Santé) in collaboration with the Universities of Nancy and Poitiers (France). During the research, the scientists explored the relationship between maternal intake of polyunsaturated fatty acids and neurodevelopment in children, also considering the role of breastfeeding.

Several studies confirm the link between Omega-3 and cognitive abilities

Omega-3s, abundant in fish oil, especially DHA (docosahexaenoic acid), are essential to ensure the proper structure, function, and cellular communication in the brain as well as the retina. DHA is one of the fundamental components of neuron membranes.

During pregnancy, fatty acids pass from mother to fetus. For this reason, there is growing interest in the negative effects of a maternal diet high in Omega-6 and low in Omega-3, which is typical of many Western diets. According to a study published in Lancet in 2007, children whose mothers consumed little fish during pregnancy had a higher risk, compared to those whose mothers consumed much fish, of being limited in verbal intelligence development, prosocial potential, motor skills, and communication. A Spanish study showed that maternal consumption of 2-3 servings of fish per week was associated with higher scores at age 4 on the McCarthy scale, a test evaluating child abilities. Additionally, an English study reported evidence of an association between low blood Omega-3 levels and reduced reading and memory capacity in children aged 7 to 9.

It also highlighted how supplementation with DHA improved these conditions. The same study pointed out that high Omega-6 concentration was associated with good reading ability, but this link lost statistical significance when controlling for sex and socioeconomic conditions of the children. All these studies directly or indirectly support the hypothesis of Omega-3 benefits in cognitive development. The role of Omega-6 remains uncertain.

The Omega-6 to Omega-3 ratio influences cognitive abilities

During the study, 2002 pregnant women between the 24th and 28th week of gestation were recruited from prenatal clinics in the Poitiers and Nancy areas. The selected volunteers, all with singleton pregnancies, were free of diabetes, planned to remain in the area, and were able to read and write French correctly.

At the start of the study, each woman reported in a questionnaire the foods consumed in the last trimester of pregnancy. It was thus possible to calculate the intake of total lipids and percentages of Omega-3 (including alpha-linolenic acid) and Omega-6 (including linoleic acid and arachidonic acid). Questionnaire analysis showed that 63% of mothers consumed less than two portions of fish per week and that only 54% of DHA intake came from this food. Omega-3 and DHA consumption was significantly higher among women who breastfed, and these women had a lower Omega-6 to Omega-3 ratio compared to mothers who did not breastfeed.

No differences were evident in Omega-6 intake. Out of the 2002 participants, nutritional information was obtained from 1585 women. The study then followed the children of these mothers after 2 and 3 years to evaluate their cognitive abilities. This phase included use of the McArthur Communicative Development Inventory to assess communication and language, the Ages and Stages questionnaire to determine developmental delay, the Peg Moving Task to evaluate manual skills, the Design Copying test to detect integrated sensory dysfunctions, and a verbal fluency test. Results showed no correlation between maternal fatty acid intake and Design Copying test outcomes in both breastfed and non-breastfed children.

A high Omega-6 to Omega-3 ratio was positively associated with Peg Moving Task performance and negatively associated with the Ages and Stages questionnaire and verbal fluency test. In breastfed children, no associations were evident between maternal total fatty acid intake and neurodevelopment, nor between Omega-3 intake and any cognitive test results. In non-breastfed children, maternal intake of total polyunsaturated fatty acids, Omega-6, and linoleic acid was negatively associated with Communicative Development Inventory and Ages and Stages test results. The Omega-6 to Omega-3 ratio was inversely proportional to scores on these tests and showed a significant interaction with verbal fluency. There was also a strong association between breastfeeding and the Omega-6 to Omega-3 ratio on the Communicative Development Inventory score, and with the verbal fluency assessment.

Breastfeeding may compensate for Omega-3 deficiency

Based on these results, researchers hypothesized that the maternal Omega-6 to Omega-3 ratio may influence development during fetal life. In any case, breastfed children may escape the negative association with Omega-6 and low Omega-3 concentration, as they can obtain Omega-3 from breast milk. Scientists pointed out that the participants had a higher socioeconomic status than average French standards, and that dietary questionnaires could not precisely assess fatty acid intake, especially Omega-3. For example, DHA intake was 170 and 148 mg per day for mothers who breastfed and those who did not, respectively—both rather low values. Despite study limitations, the data promote breastfeeding and encourage limiting Omega-6 consumption during pregnancy.  

Sources: Bernard JY, De Agostini M, Forhan A, de Lauzon-Guillain B, Charles MA, Heude B; the EDEN Mother-Child Cohort Study Group. “Dietary n6:n3 fatty acid ratio during pregnancy is inversely associated with child neurodevelopment in the EDEN mother-child cohort”. J Nutr 2013;143:1481-1488. Hibbeln JR, Davis JM, Steer C, Emmett P, Rogers I, Williams C, Golding J. “Maternal seafood consumption in pregnancy and neurodevelopmental outcomes in childhood (ALSPAC study): an observational cohort study”. Lancet. 2007 Feb 17;369(9561):578-85. Paul Montgomery,* Jennifer R. Burton, Richard P. Sewell, Thees F. Spreckelsen, and Alexandra J. Richardson “Low Blood Long Chain Omega-3 Fatty Acids in UK Children Are Associated with Poor Cognitive Performance and Behavior: A Cross-Sectional Analysis from the DOLAB Study”. PLoS One. 2013; 8(6): e66697.