Although it's an established fact that high doses of vitamin A can be toxic, it seems they can also cause defects in the unborn baby.
A major study, released early by the New England Journal of Medicine because of its importance, has discovered that pregnant women who take high doses of retinol, or vitamin A, every day increase the risk of having a handicapped baby.
The danger threshold, researchers discovered, appears to be daily doses in excess of 10,000 IU, which is four times the recommended daily allowance (RDA) for adult women. Women who take these doses, and especially during the first seven weeks of pregnancy, run a one in 57 risk of having a handicapped baby, compared to those who take just half that dose.
Birth defects reported in a study of 22,000 mothers were mainly associated either with the central nervous system or the heart.
The study also supported the other well-known fact that beta-carotene is a safer alternative to vitamin A. Apparently, the retinoids, and not the carotenoids, are the cause of birth defects. Even at high doses, beta-carotene does not raise vitamin A levels in the body sufficiently to cause defects in the unborn child (The Lancet, October 14, 1995).