21   Child murder by mother—verdict of contributing to death etc

Whosoever, being a woman delivered of a child is indicted for its murder, shall, if the jury acquit her of the murder, and specially find that she has in any manner wilfully contributed to the death of such child, whether during delivery, or at or after its birth, or has wilfully caused any violence, the mark of which has been found on its body, be liable to imprisonment for ten years.