Maternal DHA intake during pregnancy and/or lactation can prolong high risk pregnancies; increase birth weight, head circumference and birth length, and can enhance visual acuity, hand and eye co-ordination, attention, problem solving and information processing.
Fetal and infant DHA deficiencies are associated with poor growth, and brain and eye development and function.
Typically, only about 0.1% of dietary ALA is converted to DHA in normal healthy adults eating a Westernized diet making routine dietary intake of DHA a necessity in extraordinary circumstances, such as in pregnancy and during lactation.
DHA is the main structural fatty acid in nerve cells and its presence helps to ensure nerve cell message transmission through its effects on ion channels, response to neurotransmitters , and formation of secondary messengers. It may also protect against loss of scaffolding proteins and lipid peroxidation thereby maintaining the physical structure of the brain.
DHA is also extremely important for vision since it is the main membrane constituent in the photoreceptor cells of the eye. These cells are responsible for transmitting light messages to nerves that supply the brain and their proper function is essential for vision.
In the last three months of pregnancy, there is rapid accumulation of DHA in the eyes and brain of the fetus.
After birth, the baby’s nervous system continues to grow very rapidly and DHA supplied primarily through breast milk, is required as a structural component. Consequently, maternal body stores can become depleted resulting in health risks for her including post natal depression
During the last trimester, a fetus accrues about 67 mg of DHA per day from the mother, and during breast feeding the need increases to 70–80 mg daily. This huge demand for DHA particularly during breast feeding depletes maternal stores to below pre-pregnancy levels and this deficit can take months to even partially correct.