A lot of people do still say its the up regulating breast milk supply thing. I haven't looked at any research so don't know what quality of evidence there is on the issue but I do think it would be super reassuring to be able to tell women it's not a supply issue. I've had several breastfeeding Mum's tell me how desperately close they've come to swapping to formula at these times or that it's when they swapped with their previous child. Being able to reassure them that it's just extra comfort their bub is seeking would definitely make the difference between some people continuing BF or not.

Regarding the wonder weeks book, although my DD has not stuck exactly to their pattern I have found it very useful for describing stages of development I can see her going through and also age appropriate games and play ideas.