The small-scale study, published in Pediatric Research, ​supports previous research that demonstrates the importance of diet and lifestyle during pregnancy on the development of a baby – finding that adjusting the diet of healthy pregnant women to include higher levels of omega-3 could be beneficial to their babies.

"The results of our study suggest that frequent fish consumption by pregnant women is of benefit for their unborn child's development. This may be attributable to long-chain polyunsaturated fatty acids within fish, but also due to other nutrients like vitamin D and E, which are also important for development,"​ explained Kirsi Laitinen of the University of Turku and Turku University Hospital in Finland.

According to Laitinen, a mother's diet during pregnancy and breastfeeding is the main way that valuable long-chain polyunsaturated fatty acids become available to a foetus and infant brain during the period of maximum brain growth during the first years of a child's life. Such fatty acids help to shape the nerve cells that are relevant to eyesight and particularly the retina. They are also important in forming the synapses that are vital in the transport of messages between neurons in the nervous system.

"Our study therefore highlights the potential importance of subtle changes in the diet of healthy women with uncompromised pregnancies, beyond prematurity or nutritional deficiencies, in regulating infantile neurodevelopment,"​ said Laitinen – who believes that their results should be incorporated into counselling given to pregnant women about their diets.

Study details​

The Finnish research team analysed the results of 56 mothers and their children drawn from a larger study. As part of the study mothers had to keep a regular food diary during the course of their pregnancy. Fluctuations in weight before and during pregnancy were taken into account, along with their blood sugar level and blood pressure. Aspects such as whether they smoked or developed diabetes related to pregnancy were also noted.

The team recorded the levels of nutritional long-chain polyunsaturated fatty acid sources in the mother's diet, in addition to measures of blood serum, and the levels in the blood of their children by the age of one month.

Children were also tested around their second birthday using pattern reversal visual evoked potentials (pVEP) – a sensitive and accurate, non-invasive method that used to detect visual functioning and maturational changes occurring within a young child's visual system.

Analysis of these test results showed that infants whose mothers ate fish three or more times a week during the last trimester of their pregnancy fared better than those whose mothers ate no fish or only up to two portions per week.

These observations were further substantiated when the serum phospholipid fatty acid status was evaluated, said the team.