Perinatal influences on the uptake of newborn Vitamin K prophylaxis--a retrospective cohort study.

Objectives: To describe rates of newborn vitamin K prophylaxis uptake according to method of administration (intramuscular [IM], oral, refused) and identify predictors for the choice of oral administration and for refusal of vitamin K prophylaxis.

Methods: A retrospective cohort study examined the relationship between method of vitamin K administration and various exposure factors (infant, maternal, socio-demographic and healthcare professional). Written and electronic data for births from a single tertiary birthing unit in New Zealand (NZ) were examined over a four-year period from January 2009 to December 2012.

Results: Records for 7,089 mothers/babies were examined. Of these, 92.9% of infants received IM and 5.4% oral vitamin K. Refusal of vitamin K was associated with (OR [95%CI]): Asian ethnicity (5.87 [3.61 to 9.53] p<0.001); vaginal delivery (2.85 [1.83 to 4.43] p<0.001); and gestational age, per additional week, (1.24 [1.10 to 1.39) p<0.001). Oral vitamin K was associated with (OR [95%CI]): Asian ethnicity (2.61 [1.80 to 3.79] p<0.001); obstetric nurse as the Lead Maternity Carer (LMC) (2.65 [1.73 to 4.06] p<0.001); vaginal delivery (2.34 [1.84 to 2.96] p<0.001); gestational age, per week, (1.14 [1.07 to 1.21] p<0.001); and LMC experience, per decade (0.61 [0.51 to 0.74] p<0.001).

Conclusions: This study reveals several important and novel associations with mode of administration of newborn vitamin K prophylaxis. IM vitamin K uptake was also lower than international data, largely due to increased oral uptake.

Implications: Uptake of vitamin K is associated with ethnicity and also factors in the infant that might imply a perceived protection against vitamin K deficiency bleeding. Further investigation is required for a fuller understanding of the motivations for choosing differing routes of vitamin K administration in newborns, with particular emphasis on factors influencing parental choice.