M.
That happened to me too but not following the birth of my children. My hair started falling out just as you've described. I went to 2 doctors and both said it was because I was getting older. (I'm only 38)I suspected it had something to do with my changing my birth control from the pill to a copper IUD since it started falling out practically the same week I switched. I was having problems with my IUD so I had it removed and went back on the pill. My hair loss stopped overnight. I told my doctor and she said that was the first time she'd heard of that but as I researched it on the internet I learned its not as uncommon as she thought. It had something to do with estrogen. Too much/too little? I don't remember. Hope this helps.
M.