OBJECTIVE: To assess the effect of prenatal vitamin K1 on the coagulation status of newborns. METHODS: 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. RESULTS: 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). CONCLUSION: 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.
OBJECTIVE: To assess the effect of prenatal vitamin K1 on the coagulation status of newborns. METHODS: 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. RESULTS: 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). CONCLUSION: 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.