i have stumbled upon THE pregnancy book must have! it's called "the complete organic pregnancy; what you need to know - from the nail polish you wear to the bed you sleep in to the water you drink" by deirdre dolan & alexandra zissu.
i know it's a mouthful but the things i've learnt from this book is indispensable. i would actually recommend this book not only to women who are pregnant but to ALL women. it's so informative and at the same time so scary. it basically tells you what chemicals are in AND around everyday items you use and they give you alternatives. it tells you what to look out for, the big no-nos.
the authors are journalists themselves so this book has been thoroughly researched. the two must read books while trying to conceive or while pregnant (in my books at least):

• the complete organic pregnancy (which talks about the environment you're in and how to have the safest AND healthiest pregnancy possible by minimizing your exposure to the toxins around us)
• what to expect when you're expecting (which talks about how your body changes and how the baby is growing and when to worry and when not to, eg bleeding and spotting)

these two books are my fortress of knowledge on pregnancy. i even highlighted notes on the pages! (if only i studied this hard back when i was in school............................)