About 30 years ago I read a book about America in the late 1800's,
involving Russian (or German) immigrants and American pioneers.  One
of the Russian (or German) immigrants was named Karl, and he fell in
love with an American girl (the heroine).  The girl also was attracted
to an American boy, that her family really wanted her to marry. 
However, almost against her will, she fell in love with Karl.  Her
father was prejudiced and would not accept the marriage. There was
also an immigrant girl with long blond braids who was in love with
Karl.  After the heroine and Karl share a night of pre-nuptial love,
she says she may go back to her American boyfriend.  Karl says, "Think
you I would let you go to him now?  We may haf a child from this
night."  Karl and the heroine eventually get married, and the
heroine's family moves further west, but not until her mom gives her a
book about childbirth.  I've forgotten the name of this book and I
really would like to read it again.