Anonymous asked in Pregnancy & ParentingPregnancy · 1 decade ago

Why do people commonly say pregnancy is 9 months when it's actually 10?

I've always been confused by this...

9 Answers

  • 1 decade ago
    Favourite answer

    Pregnancy weeks are different than regular weeks. Week one starts the week of your first day of your period. At that point your not pregnant, but still that counts as week one. So pregnancy weeks go from 1-40 but at weeks 36-40 you are actual in the nine month. I am 17wks, and this the last week on my fourth month. Then weeks 18-21 are month five.

    Its confusing and no need to know if your not pregnant. I guess its how doctors keep everyone on the same page and the basis of how babies grows is a 40wk process.

  • 1 decade ago

    When you calculate a pregnancy with a 4 weekly month then it's 10 months, but most people forget there is more than 4 weeks in the month, which adds up in time, therefore it's only actually 9 months, sometimes 9 and a half.

    It's much less confusing to just go by weeks instead of months in my opinion.

  • Ista
    Lv 7
    1 decade ago

    It is 9 months. People commonly forget that there are more than 4 weeks in a month. A month is 30-31 days. 4 weeks is 28 days. Those extra 2-3 days each month add up over time.

  • Because its not 10 months. you are pregnant for 9 FULL months. going 4 weeks per month. you might go past that but you'd be over due. so some people hit the 10 MARK but no one is pregnant for 10 full months as they do for 9. =)

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  • 1 decade ago

    Because it is only 9 gregorian months. if you went by 4 weeks for every month we would actually have 13 months in a year

  • 1 decade ago

    I have no drives me crazy! Right now I have a little less than 4 weeks to go and into my 9th month. Do the rough math...40 weeks at roughly 4 weeks per month = 10 months!!!!!!!!!!!!!!!!!!!!!!!!!!!

    Source(s): my current life and easy math!!
  • plus they always add 2 weeks to your pregnancy for implantation and other things

  • Anonymous
    1 decade ago

    because normally it would be 9 months but some people make it to ten

  • Anonymous
    1 decade ago

    it depends on your the baby if he/she is ready to come out yet

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