palkovic87 posted this awhile back and i'm reposting, I believe she got this info out of a book.
weeks 1-4=1 month
weeks 5-8=2 months
weeks 9-13=3 months
weeks 14-17=4 months
weeks 18-22=5 months
weeks 23-27=6 months
weeks 28-31=7 months
weeks 32-35=8 months
weeks 36-40=9 months