Be Well Reader
Ina May's guide to childbirth by Ina May Gaskin — This book is more focused on midwifery and those who do not wish to have a more medical-focused birth in a hospital. That said, there is a substantial amount of information in here that would be useful even for a hospital birth. Would recommend for pregnant women or their partners who are interested in learning more about the birthing process in general.
Although this book is targeted toward dads, and despite the somewhat cheesy approach to the topic, I thought this had some great suggestions for anyone who might be involved in the labor and delivery process as a support person. Dealt with some of the gorier details in a matter-of-fact and practical way.
The dad's playbook to labor and birth: a practical and strategic guide to preparing for the big day by Theresa and Brad Halvorsen