Is the vitamin K injection at birth neccessary?

What the evidence says

Babies are born with very little vitamin K, and breast milk doesn't provide much either, so without extra vitamin K some infants develop dangerous bleeding, including bleeding in the brain, in the first weeks to months of life. The Canadian Paediatric Society and College of Family Physicians of Canada, along with the American Academy of Pediatrics and CDC, all recommend a single injection of vitamin K into the thigh muscle within the first hours after birth for every newborn.

An oral (by-mouth) option exists, but it requires three separate doses over the first two months and is less reliable at preventing bleeding, even when all doses are given as directed. Canadian guidelines say the oral route should really only be used if parents decline the injection, and note that even injected vitamin K doesn't remove all risk, especially in babies who are exclusively breastfed with low vitamin K intake.

A study in the early 1990s raised a concern that the injection might be linked to childhood leukemia. This prompted several large case-control studies and a pooled analysis in Britain and Germany afterward, and these did not find convincing evidence of a cancer link, though a very small residual risk could not be completely excluded in some analyses. Health agencies consider the proven benefit of preventing serious bleeding to clearly outweigh this theoretical, unconfirmed risk.

The shot itself is considered very safe, with only minor, temporary soreness or redness at the injection site reported. You can reduce your baby's discomfort by holding them and breastfeeding during the injection.