DHA has to come from mom in utero, and needs to be in formulas/breast milk after birth.
Studies have shown behavioral, IQ, and developmental benefits of higher DHA levels in the infant diet, whereas others have not.
Breast milk levels of 1% (compare to the less than 0.2% in American milk) are completely safe for the baby. All baby formula makers now enrich their products with DHA, and often to levels that are higher than commonly found in American breast milk. The reason for this is to match the worldwide average DHA level in human breast milk (about 0.32%).