5 months 1 week. Pregnancy is 40 weeks so if you divide that by 4 (roughly a month) you get 10 so pregnancy is 10 months. That's the easiest way I work it out and makes most sense.
5 months begins at 18 weeks you're not pregnant for 10 months only 9 when you calculate your months you always need to remember there is always at least 3 extra days in the month so a month is over 4 weeks so you can't count your months as just 4 weeks
Take the number of weeks and divide by 4 and that number is how many months you are
5 months is 22 weeks is what Google says