Objective To explore the influencing factors and reasoning of parents who opt out of intramuscular vitamin K prophylaxis for their newborn.

Design We conducted a qualitative study with 15 families from the Otago/Southland region of New Zealand. Semistructured interviews explored their choice to opt out of intramuscular vitamin K prophylaxis and thematic analysis was used to elucidate themes that captured important aspects of this parental decision-making process.

Results Parents opt out of intramuscular vitamin K for a variety of reasons. These were clustered into three main themes: parents' beliefs and values (philosophy and spirituality), concerns about their child's welfare (pain and potential side effects) and external influencing factors (family, friends, media and health professionals). As part of a wider family hesitancy towards medical intervention, the majority of parents also raised concerns regarding other perinatal or childhood interventions.

Conclusion Many factors influence parental decision making and lead to a decision to opt out of newborn intramuscular vitamin K prophylaxis. Due to strong parallels with other common childhood interventions, these findings have relevance for vitamin K prophylaxis and for other healthcare interventions in childhood.