Informed consent may well have been given prior to the birth of the baby and forgotten about in the drama of birth - I'm not stating this as a fact, but a possible reason for this parental reaction. But midwives have a lot to think about during and after delivery, and the injection of Vit K will be ingrained and totally automatic. I think the infant would have more to complain of by being born than by having an injection (apologies for the mild flippancy) Vit K can be given orally, but it needs several doses, if I recall correctly, so there's room there for mistakes and accidentally omitted treatment.