"From a public health perspective, this is an important insight. It highlights how pregnancy and the newborn period is a critical time for education and support to promote public health initiatives," he said.
"Maintaining high immunisation rates in New Zealand is vital to ensure our children do not fall prey to sometimes deadly infectious diseases that we thought we'd left behind."
Vitamin K is given to newborns to prevent Vitamin K deficiency, which can in rare instances lead to severe bleeding and death.
Of the 3,575 babies born in Dunedin in 2010 and 2011, 3 per cent of parents declined Vitamin K for their babies.
Of those, 17 per cent went on to decline all early childhood immunisations, usually given at 6 weeks, 3 months, 5 months and 15 months. They were also more likely to be late for 6 week immunisations, which gives infants a greater risk of catching diseases such as whooping cough.
For parents who consented to Vitamin K, only 1.2 per cent declined immunisations.
The findings of the study are published in the international Journal of Paediatrics and Child Health.