According to US law, when a person approaches a woman who is pregnant in the third trimester, usee a knife and "takes the life of the unborn child" while the woman survives, is this crime a murder or a personal injury to the pregnant woman, or both?
Does anything change depending on the month that the pregnancy had reached?
Murder is most often prosecuted by the states, not the US government, and each state greatly varies on the subject. Some states consider a fetus to be a person at any stage in its development; some require harsher punishments if the defendant knew the victim was pregnant; and some have no specific mentions of whether a fetus makes any difference in the law. You can see a great breakdown of the various laws and how they are applied to fetuses in this per-state table.
Any federal crimes that are prosecuted by the US federal government are also subject to the Unborn Victims of Violence Act which recognizes a fetus as a victim if it is injured or killed while committing a list of federal crimes.
