Because you have to have sex and hopefully enjoy it before you get to the birthing part.  This book is very insightful and emphasizes that women deserve to have good orgasmic sex too!

Using this book to understand your body and it's natural cycle is a powerful way to first prevent, then ultimately acheive pregnancy.  This classic gives you the information and charts you need to practice natural family planning. 

The birth stories in this book are so empowering and beautiful!  Ina May has a fanastic no nonsense tone in the resource section of the book that really resonates with the reader.  Her Sphincter Law chapter is worth the read for any expectant woman!

Goer explains in a very readable and enjoyable style the most up to date scientific information (evidence-based) about pregnancy and birth, and all the medical interventions surrounding birth.

This is one of the top all around reccomendations for a couple wanting to pursue a natural childbirth.  It's the ultimate guide for any one who will be in a position to support a laboring woman.

If you want a VBAC, this book will show you how to get one. 

 It's an accessible book and a good read. It's not only for midwives, but also a great resource for parents about pregnancy and birth. The revised edition also includes information about herbs, homeopathy, water birth, sexuality, etc.

This is a very thorough book about PPD. The authors provide invaluable resources and a lot of self-help information. 

Given the rate of sexual abuse among women (estimates range to as high as 1 in 3) the topic of how sexual abuse might affect chilbirth is relevant. Simkin and Klaus explore the issues compassionately and thoroughly.

A great general reference, spanning topics from pregnancy to the newborn. This is a great supplement to a childbirth education class, and for those who may not be able to take a class (for financial or other reasons) it's readable, and thorough.

This book describes how early civilizations viewed women's bodies as sacred because they produce life and how patriarchy eventually succeeded in suppressing these ancient goddess worshipping communities.  A dense, but incredibly evocative read.

This book is amazing!  Be careful, it might make you want to become a Midwife.