Colostrum is naturally rich in vitamin K, so if you're taking a supplement you should be good to go. There are risk factors, such as long or extremely fast pushing stage, use of forceps or vacuum, mother's use of antibiotics/anticoagulants/anticonvulsants during pregnancy, family history of liver disease, and so on. If you're having a boy and plan to have him circumcised, you should probably get it, unless you are following the Jewish tradition of 8th day circ, since vit. K peaks in the system on the 8th day. If you don't have any of those risk factors, I would skip the shot if you're nursing. That's what we plan to do. There are a LOT of risks associated with the vitamin K shot, and fewer than 2% of infants actually need it -- and many of those could do just as well if certain risk factors would be avoided during pregnancy. I have some links and would be happy to PM you if you like.