"Expecting Better" tends to 'cherry-pick' the studies that best suit the author's viewpoint. For example, the section on exercise says that exercise doesn't matter. This is false -- both books I mention below describe numerous studies suggesting that fitter women have easier labors and recoveries (this makes sense -- labor and birth are physically demanding, strenuous activities). Example 2: the section on gender effectively states that medical science has no way of knowing how the sex of the fetus is determined. This is also false. The "Chocolate" book below describes studies indicating that the testosterone level in the sperm influence how the sex of the fetus is determined.
Unfortunately, I was expecting science writing of the caliber of "Do Chocolate Lovers Have Sweeter Babies?" and "Hands Off My Belly!". Written by a PBS science writer and two OBs, respectively, these books demonstrate deeply nuanced understandings of the medical literature and have provided me with solid advice about how to manage my pregnancy and some ideas about how I want the baby to be treated immediately following birth.
"Expecting Better" is written by an economist -- not a doctor and not someone with a background in the natural sciences. While I can appreciate her quantitative analysis and statistical savvy, I really wanted science, not math. I bought it on the recommendation of Maggie Koerth, BoingBoing's Science Editor; she wrote a blog post recommending a few science-oriented books on pregnancy: http://boingboing.net/2014/06/02/eight-evidence-based-pregnancy.html (I'm hoping Bumpology proves to be more deeply engaged with extant medical literature).