halacha - At what point is a child considered living

Does life begin at conception, or does Judaism take a different view? At what point does life begin?

Answer

For most halachic purposes, life begins at birth - to be exact, at the emergence of either most of the head for a normal birth, or most of the body if it's a breech birth (Niddah 28a). For that reason, if a pregnancy is endangering the mother's life, an abortion may be performed (see Shalom's answer here), whereas once the head has emerged we may not do so, because that would be outright murder (Sanhedrin 72b).

Generally, though, a baby less than 30 days old is considered possibly non-viable; for that reason, if he dies (G-d forbid) during that time, his parents don't sit shiva for him (Shulchan Aruch, Yoreh De'ah 353:4).