I’m not sure about the chloroform either, although I consider it a possibility. It could also be an accident—maybe she left the wee one hidden in the trunk while she partied, and the child died from over-heating. If so, it was a convenient accident, because I believe she intended to get rid of that inconvenient child.
Oh, I hope to God she didn’t leave her in the trunk - alive. Imagine the fear of the poor child. Some things we’ll never know.