Prevalence of subclinical vitamin K deficiency in Thai newborns: relationship to maternal phylloquinone intakes and delivery risk.

BACKGROUND

Vitamin K deficiency bleeding (VKDB) in infants is a rare but serious worldwide problem, particularly in Southeast Asia. Apart from exclusive breast feeding, little is known of the maternofetal risk factors that predispose infants to VKDB.

OBJECTIVES

To assess (a) the relationships between functional vitamin K insufficiency in a large cohort of Thai mothers to that of their newborn infants and (b) the importance of delivery risk factors and maternal intakes of vitamin K as determinants of neonatal vitamin K status.

METHODS

Vitamin K status was assessed by measuring undercarboxylated prothrombin (protein induced by vitamin K absence/antagonist-II (PIVKA-II)) in 683 mothers and in the cord blood of their babies by sensitive immunoassay. Dietary phylloquinone (vitamin K(1); K(1)) intakes were assessed in 106 of these mothers by food frequency questionnaire.

RESULTS

Babies were categorised as 'normal' (n=590) or 'high risk' (n=93) according to birth weight and delivery type. PIVKA-II was detectable (>0.15 arbitrary units (AU)/ml) in 85 mothers (12.4%) and 109 babies (16.0%) with median levels of 0.78 and 1.04 AU/ml in mothers and babies, respectively. 'High-risk' babies had a higher median detectable PIVKA-II concentration than 'normal-risk' babies (3.1 vs 1.0 AU/ml, p=0.02) and a higher prevalence of clinically relevant (>5.0 AU/ml) concentrations (p=0.006). Mothers with K(1) intakes below the US recommended 'adequate intake' for pregnancy (<90 microg/day) had a higher prevalence of detectable PIVKA-II (18.8%) than those with adequate intakes (3.3%) (p=0.01).

CONCLUSIONS

Functional, clinically relevant, vitamin K insufficiency was more common in 'high-risk' than 'normal-risk' newborns. Vitamin K insufficiency in mothers was linked to lower dietary K(1) intakes during pregnancy.