Vitamin K in preterm breastmilk with maternal supplementation.

Six healthy lactating mothers who gave birth to preterm infants at a median post conceptional age of 29.5 (range 26-30) weeks were given 2.5 mg phylloquinone (vitamin K1) orally daily for 2 weeks beginning at a median postconceptional age of 31.5 (range 28-32) weeks. Phylloquinone was measured in the breastmilk daily for 14 d. Trough plasma phylloquinone concentrations were also determined on four occasions. Phylloquinone levels in the breastmilk increased from a baseline of 3 +/- 2.3 ng ml(-1) to 22.6 +/- 16.3 ng ml(-1) (mean +/- SD) after the first dose (p < 0.05); a gradual increase was noted until phylloquinone levels reached a plateau of 64.2 +/- 31.4 ng ml(-1) after the sixth daily dose.