Effect of maternal pyridoxine X HCl supplementation on the vitamin B-6 status of mother and infant and on pregnancy outcome.

The effect of maternal pyridoxine X HCl (PN-HCl) supplementation on the vitamin B-6 status of pregnant women and their infants at birth and on pregnancy outcome was investigated. Volunteer subjects were randomly assigned a daily vitamin B-6 supplement containing 0, 2.6, 5, 7.5, 10, 15 or 20 mg of PN-HCl in a double-blind study. The mean dietary vitamin B-6 intake of the group was 1.43 +/- 1.28 mg/day as estimated from 24-hour dietary recalls. Maternal plasma pyridoxal 5'-phosphate (PLP) levels were positively correlated with vitamin B-6 supplementation at 30 weeks gestation (r = 0.55, P less than 0.0005) and at delivery (r = 0.54, P less than 0.01). Cord plasma PLP levels reached a maximum when maternal PN-HCl supplementation was 7.5 mg and greater. Supplemental PN-HCl at the 7.5-mg level was required to prevent a decrease in maternal plasma PLP at delivery. Apgar scores at 1 minute after birth were higher (P less than 0.05) for infants whose mothers took 7.5 mg or more supplemental PN-HCl than for infants of mothers who took 5 mg or less. These findings indicate that a vitamin B-6 intake between 5.5 and 7.6 mg/day (diet plus supplement as pyridoxine equivalents) was required to maintain maternal plasma PLP levels at term at a level comparable to initial values.