Pregnancy by month

Does anyone else go by this ?

Month 1: weeks 1-4

Month 2: weeks 5-8

Month 3: weeks 9-13

Month 4: weeks 14-17

Month 5: weeks 18-22

Month 6: weeks 23-27

Month 7: weeks 28-31

Month 8: weeks 32-35

Month 9: weeks 36-40