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.