Pregnancy outcome following use of large doses of vitamin B6 in the first trimester.

Vitamin B6 is often prescribed for the treatment of nausea and vomiting of pregnancy (NVP), at much higher doses than initially recommended. Large doses of vitamin B6 have been associated with cases of neuropathy. We set out to assess whether higher than standard doses of vitamin B6 during the first trimester of pregnancy were associated with a risk of maternal adverse events, major malformations, miscarriages or low birth weight. This was a prospective comparative observational study. The study group included women who were exposed to >50 mg/day of vitamin B6 during the first trimester; the control group included pregnant women with a non-teratogen exposure. A total of 192 pregnancies were followed-up. The mean dose of B6 used in the study group was 132.3 mg/day (median 110 mg/day, range 50 - 510 mg/day), for a mean period of 9 +/- 4.2 weeks. In this group (n = 96), there were 91 live births, one major malformation and the mean birth weight was 3,542 +/- 512 g. There were no statistical differences in the study endpoints between the vitamin B6 and the control groups. Within the limits of our sample size, higher than standard doses of vitamin B6 do not appear to be associated with an increased risk for major malformations.