Although somewhat dated now in terms of medical development, I would suggest getting this book for the development chapters and for the great photos. The development section even covers day-to-day development at some points, and is a fascinating read if you are pregnant or even just curious. I highly recommend buying this book if you can find a copy.

Having worked in the field of mouse genetics for years now, i have found this book to be an incredibly useful source which provides the researcher with many details that could provide the foundations to many projects.