My favouite pregnancy books are:
-'Gentle Birth, Gentle Mothering: The Wisdom and Science of Gentle Choices in Pregnancy, Birth and Parenting' by Dr Sarah J Buckley
-'Birth Right' by Susan Ross
-'Birth Your Way' by Sheila Kitzinger
They are all very holistic but also informative and I found them very inspiring. Particulary good if you are interested in birth centres or homebirth.