They point out that supplementing from mid-pregnancy to the 34th week is perfectly safe.
After birth, from 1 to 8 months of age, DHA continues to accumulate at a slower rate in the baby’s body. After about 2 years of age brain DHA practically reaches adult levels.

Since breastfeeding is the only source of nourishment for the newborn for the first 6 months of life, it is important to ensure that the breastfeeding mother has adequate stores of DHA as well. In another study, supplementation of infant formula with DHA during the first weeks of infancy was found to improve the mental function.

Major food sources of DHA
Fishes such as salmon, tuna, sardines and mackerel; fish oil supplements, nuts, seeds, oils like soyabean oil, rapeseed oil, linseed oil, flaxseed oil, eggs and marine algae are rich in DHA.However, excessive cooking of these foods may destroy DHA.
DHA is available as a supplement in two common forms:
• Fish oil capsules, which contain both DHA and EPA
• DHA from algae, which contains no EPA