Blood in vomit
In the early days after the birth, many babies will vomit up mucous from their stomach. This is mostly the remnants of the amniotic fluid that was swallowed in the womb, mixed with mucous produced by the lining of the baby's stomach, in preparation for absorbing milk feeds. Occasionally, the mucous can be quite thick, and the baby may temporarily gag on it in the back of their throat. This can cause them to look like they are choking, and possibly go red, or blue, in the face. Understandably, parents find this quite distressing to watch, however babies will usually tend to deal with it OK, on their own. Sitting your baby upright, or placing them over your shoulder, will generally help them to swallow the mucous (or spit it out).
Once the baby is taking larger volumes of milk, it is very normal for them to vomit, or 'regurgitate', part of their milk around feed time. (However, some babies do not vomit much until they are about 2 to 3 months old.) Your baby may vomit a lot, or only on occasions. (If you are lucky, they won't at all, unless they are physically unwell). Most babies will tend to vomit 'off and on' at various stages during the first 12 months of their life. A few babies will have problems associated with vomiting, due to reflux
Your baby may have little 'delicate' vomits that just overflow gently from their mouth, or they may vomit with dramatic style, in a great gush coming from their mouth and nose! (A very attractive party trick!) Observing this type of vomit can leave parents feeling very concerned (and possibly astonished, at the sheer force of it), or upset about all the milk that has 'gone to waste'. Unlike adults and older children, babies vomit quite effortlessly, and don't often seem disturbed, or distressed by it.
The most common cause of a baby vomiting in the early weeks is by some of the milk being brought up with a pocket of air, when the baby burps.