canada
See Criminal Code, s. 223:
223 (1) A child becomes a human being within the meaning of this Act when it has completely proceeded, in a living state, from the body of its mother, whether or not
(a) it has breathed;
(b) it has an independent circulation; or
(c) the navel string is severed.
(2) A person commits homicide when he causes injury to a child before or during its birth as a result of which the child dies after becoming a human being.
For the act to be homicide of the child, the child needs to exist in a living state outside of the body of its mother. The act that is considered homicide can occur before the child leaves the mother's body, though.
The homicide would be categorized as murder if
- the death of the child was intended or
- the accused intended to inflict bodily harm to the child knowing that death was likely and the accused was reckless as to whether death ensued.
The homicide would be categorized as manslaughter if the risk of bodily harm to the child was reasonably foreseeable. See e.g. R. v. Prince, [1986] 2 S.C.R. 480 (beware: disturbing facts).
If the child does not ever exist alive outside the body of the mother, it is not a homicide of the child. See discussion in R. v. Drummond (1996), 112 C.C.C. (3d) 481, paras. 39-50 (Ont. Prov. Div.) (beware: disturbing facts).