This has been used as natural contraception, with greater than 98 % effectiveness during the first six months after birth if specific nursing behaviors are followed. (en.wikipedia.org)
It's also possible this behavior is a odd manifestation of a hold - over of nursing behavior. (stevedalepetworld.com)
The only thing I would change is to go back a couple years and know that it was totally OK to set some limits on my daughter's nursing behaviors during my pregnancy. (ababyonboard.com)