Research indicates that vitamin B7 (biotin) is broken down more rapidly during pregnancy and that biotin nutritional status declines during the course of pregnancy (6, 8, 9). Although the level of biotin depletion is not severe enough to cause diagnostic signs or symptoms, such observations are sources of concern because biotin deficiency without clinical signs or symptoms (‘subclinical’) has been shown to cause birth defects in several animal species (10).

 

Currently, it is estimated that at least one third of women develop marginal biotin deficiency during pregnancy (11). Indirect evidence also suggests that marginal biotin deficiency causes birth defects in humans.

 

The potential risk for abnormal development of the embryo or fetus (‘teratogenesis’) from biotin deficiency makes it prudent to ensure adequate biotin intake throughout pregnancy. Since pregnant women are advised to consume supplemental vitamin B9 (folic acid) prior to and during pregnancy to prevent neural tube defects, it would be easy to consume supplemental biotin (at least 30 mcg/day) in the form of a multivitamin that also contains at least 400 mcg folic acid. Toxicity at this level of biotin intake has never been reported (see Safety).