But World Enough and Time

Robin Parker and her brother, Dean, stumble onto Elizabeth, who is being brought forward through time from her native seventeenth-century England. Elizabeth thinks Roger, the man who put her in the castle, is a magician. Robin quickly realizes that Roger is a time traveler from the future. With a hand-held time machine, the three travel back to Elizabeth's time to establish her back in her own time, though in another village to prevent Roger from finding her again. 

But another time traveler, Donald, is intent on getting Elizabeth back and thanks to his machinations, Robin, Dean, and Elizabeth are forced to flee first one village, then the next. Even London doesn't provide the cover the three need. Worse (or better) yet, Dean and Elizabeth fall in love. No matter how much Robin wants to keep time traveling, it's pretty clear that Elizabeth doesn't belong in her own time any more than she does in the twenty-first century. However, the attempt to go home goes disastrously awry. Elizabeth is pregnant and Donald is not far behind.