Vitamin K deficiency bleeding affects 1 in 10,000 newborns and is almost completely preventable by giving an injection or oral solution of vitamin K shortly after birth.
I chose the oral solution as I didn't like the idea of my newborn DS having an injection so soon after birth. This did mean that the oral solution had to be given again at a later date (can't remember the exact details to be honest). The injection is just a one off.
There is some quite useful info on this website re: pros and cons:
I chose for my baby not to have vitamin K. He had a non-traumatic birth and I make sure I get lts of vitamin K in my diet as i'm fully breastfeeding. Have a read of this article, for a different viewpoint from the usual. www.aims.org.uk/Journal/Vol13No2/vitk.htm -