Niddah 29: When is a Child Actually Born? Unusual and Other Births

Rabbi Yochanan and Rabbi Elazar debate about what defines the birth of a child.  Must the bulk of a baby's head come out first, or must the bulk of the embryo be born?  The rabbis consider how much of a baby must be seen to be considered "born".  They also discuss think about what should be considered to be an unusual birth.  They wonder about twins, particularly when one twin is partially born and then the other twin is born first.  In such a case, is the firstborn the first or second child to be seen?  What if the first child is then born still?  The rabbis also discuss the difference between a stillborn baby and an embryo born in pieces.