Lyric discussion by wanderingaloud 

Cover art for A Bower Scene lyrics by Decemberists, The

Continued literal/creative translations:

"Yo sis," Margaret's (probably older sister) asked "when is your water going to break? (when is the baby due?) and what hot-headed rude guy is the father? (of the baby)"

And when Margaret started to get fatter/show the baby bump the fruit of her love (rape-baby) started moving all around in there so she went off alone back to the forest [where she first got sexually assaulted... seems logical]

The album is a concept album. It's not a rape baby, "The fruit of your love" refers to the baby she concieved in the forest willingly. The whole album is one story. There are loads of run downs on the story online, it's quite a nice, Dark fairy tale.