Late-onset vitamin K deficiency bleeding in an extremely preterm infant fed an exclusively human milk-based diet

All newborns need extra phylloquinone (vitamin K₁; K₁) to prevent vitamin K deficiency bleeding (VKDB). In preterm babies, the main sources are prophylactic K₁ given at birth and parenteral and/or enteral feeding thereafter. Preterm babies are at risk of late-onset VKDB if ongoing K₁ supplementation is inadequate. For extremely preterm infants fed an exclusive human milk diet, the low K₁ content of human milk may predispose them to vitamin K deficiency. Human milk fortification with either bovine milk-derived fortifier or human milk-based fortifier (HMF) made from pooled donor milk is a widely used strategy to improve the micronutrient and growth status of preterm infants. However, the K₁ content of HMF is markedly lower than that of bovine-based preparations. We present an unusual case of late-onset VKDB in an extremely preterm infant who received an exclusive human milk diet and HMF and quantify total K₁ intake prior to the bleeding.