During pregnancy blood levels of DHA increase to provide the developing fetus with this important fat. DHA acts as a key structural component of cells within the brain, as well as the retina of the eye. Pregnant women in North America, and most parts of the world do not consume enough DHA and therefore deficiency signs occur during pregnancy. These deficiency signs are not dangerous, but discovered due to the fact that the body begins to synthesize unique fats not normally created in an attempt to compensate for the transient DHA deficiency present during pregnancy (osbond and mead acid).
When a woman becomes pregnant a second time, the level of DHA achieved in the blood during the first pregnancy is not achieved during the second pregnancy. Body stores were depleted during the first pregnancy and not restored. There is now an even more compromised supply of DHA available for the second developing infant. Supplementing DHA in pregnancy has been shown to increase plasma levels of DHA, and deliver the DHA to the developing fetus. DHA content of breast milk is also increased as a result of DHA supplementation.
DHA supplementation during pregnancy and lactation ensures that the developing infant obtains adequate amounts of this fat.
Are there additional benefits?
A number of studies have examined the ability of DHA supplementation in pregnancy to impact the following in children; mental development and IQ, visual development, and auditory development. Some of the studies indeed demonstrate that children whose mothers were supplemented achieve greater IQ, quicker mental development, as well as sharper visual and auditory acuity. Not all studies show these benefits. Some show no effect. No study in pregnant women has yet to demonstrate detriment from using DHA supplementation. So from a risk and benefit perspective, the potential benefits seem to heavily outweigh the harms.
The placenta and the breast select for DHA. If the sole basis for utilizing fish oil during pregnancy is to supply the baby and mom with DHA, a DHA based oil should be sought. If fish oil is being used to improve mood or behaviour, or to relieve pain, a higher EPA oil would be used. In pregnancy, a high EPA oil would could still be appropriate. The DHA present in the oil would be available to supply the developing infant, while the EPA would not reach the infant, but would be available to contribute to mood and behaviour stabilization in the mother.