Can prenatal vitamin K1 (phylloquinone) supplementation replace prophylaxis at birth?

To assess the effect of prenatal vitamin K1 on the coagulation status of newborns.We measured noncarboxylated prothrombin and performed the Normotest in two groups of 5-day-old infants whose mothers were given oral vitamin K1, 10 mg/day for 2 weeks at least 10 days before delivery, or were untreated.Noncarboxylated prothrombin was found in one of 74 treated women and 13 of 186 controls, a nonsignificant difference. The mean (+/- standard deviation) Normotest value was 59.6 +/- 10.1% (range 38.9-84.4) for the treated group and 53.4 +/- 9.9% (range 16.3-89.9) for the controls, a statistically significant difference (P < .001).Based on the Normotest results, we suggest that vitamin K crosses the placenta and persists to activate the vitamin K-dependent coagulant factors until at least the fifth day of life. Thus, prenatal vitamin K1 administration may replace prophylaxis at birth.