Pendulum, I would agree with you in that women pay more attention to those studies or believe in things that reinforce their choice whether to WOHM or SAHM.
However, I do feel that on the issue of childcare, women who would otherwise wish to return to work after maternity leave, might read a Steve Biddulph or a damning bnursery report and decide at that vulnerable time in their life to stay at home instead.
My feeling towards the end of my maternity leave with No.1 was that I had to come to terms with a less family-friendly employer, fight for flexible working, reconcile myself to being taken off the career track, dealing with a difficult clingy baby who I questioned whether would settle in a nursery, work out how to do a nursery run and run a house with dh when I got home etc
If I read that I could in addition to all the above be 'damaging' my baby, I might just jack it in. Fine if SAHM was already on the cards. But not fine if the decision was made in frustration without a proper appreciation of how difficult it is to get back onto the same track years later (in my line of work, that would most certainly be true) and the increased vulnerability of being a SAHM, particularly financially.