Loved it! If you are the type of person that likes data and statistics, and wants to know WHY all these conflicting "rules" about pregnancy exist, this book is for you. I wish I had read it at the beginning of my pregnancy rather than in month 9 -- but it wasn't out yet!
Oster's big idea is that women should be trusted with specific, accurate data so they can make their own decisions based on the risks vs. rewards.
For example, perhaps you have seen all the lists of foods you're supposed to avoid while pregnant. None of these lists agree, nor do they identify which foods are more risky than others. Oster dives deep into the existing studies that have been done, examines different foods and identifies exactly which foods have risks of causing which illness, and which are more likely to cause an illness than others. You might wonder: Why take any risks at all when it comes to your baby? Well, when you are 8 months pregnant, your feet and hands are swollen (or any number of other unpleasant pregnancy symptoms), you can barely muster enough energy to get up and down from the couch, and you're ravenous for a sandwich, it may be helpful to know that your risk of getting sick from eating deli meat is actually REALLY low overall, but slightly higher for turkey than for other meats. When you know that the odds are EXTREMELY low that this sandwich will be detrimental to your baby, but there is a 100% chance that the sandwich will be the highlight of your otherwise long and uncomfortable day, along with providing protein and carbs and veggies while helping you avoid the fried chicken sandwich you might have otherwise eaten, the choice is clear. (At least, it was clear for me - another woman may decide that no risk is worth the reward, and that's fine too.)
I found the discussion about the caffeine/miscarriage link really fascinating. It makes total sense - it's likely not that caffeine causes miscarriage, but that hormones cause both a lack of desire to drink caffeine (due to nausea) and successful pregnancy. And it's difficult to prove otherwise.
And then there's alcohol. If you're like me and you enjoy knocking back a few (or at least you did, pre-pregnancy), you'll read this section with great interest. Oster's "study of studies" points to a green light for up to one drink a day in late pregnancy. Now, I didn't drink that much, but in month 9 when trying to make it through another work week, it was such a relaxing treat to have a guilt-free half-glass of wine once in a while. Again, for some moms, they may not enjoy drinking that much and so the reward isn't worth the perceived risk. For me, having a drink here and there helped me carry my baby to nearly 42 weeks with a positive, relaxed attitude.
The only section I wasn't totally on board with was the one about exercise. Oster seems to conclude that it makes no difference if you exercise while pregnant or not, though she grudgingly acknowledges that yoga has been proven to be helpful. Perhaps there's just a lack of data here, but I wish she'd been more positive about the effects of exercise in general and yoga in particular. I personally found that exercise, especially yoga, clearly gave me more energy, reduced leg cramps, improved my strength and balance as my body changed drastically, and improved my mood, with effects only becoming more noticeable as the pregnancy wore on. I'm sorry that women might get the impression from this book that exercise during pregnancy is unnecessary or unhelpful.
Again though, the main point is that women should have the information and be trusted to make their own decisions, with guidance from their doctor. The prevailing attitude that women should blindly follow vague recommendations to avoid everything from soft cheese to lukewarm hot tubs is supremely unhelpful and condescending. Some have argued that Oster is an economist, not a doctor, and has no business writing a book about pregnancy. I would counter that no one in the medical profession in the U.S. has written such a sensible, respectful and comprehensive book about pregnancy based on evidence-based medicine that answers the questions that women most want to know. Until they do, I'm sticking with Oster!