Flowers asked in Pregnancy & ParentingPregnancy · 1 decade ago

Why do people always say that a pregnancy lasts 10 months?

A pregnancy is 9 months, not 10. If there were only 4 weeks in a month there would be 13 months in a year not 12. I have a friend who's baby was born April 1st & she keeps saying that he's 7 months old.

24 Answers

  • 1 decade ago
    Favourite answer

    Pregnancy math is very strange. First of all, they start counting from the first day of your last period, not when you actually conceive. So before you're even pregnant, you're 2 weeks pregnant! An average pregnancy lasts 40 weeks so to make the math easy, most people just divide that by 4, getting 10 months. However, not every month has 4 weeks.

    For example, take my dates. My LMP was August 10, and I am due May 17, 2010.

    August - 3 weeks

    September - 4.5 weeks

    October - 4.5 weeks

    November - 4 weeks

    December - 5 weeks

    January - 4 weeks

    February - 4 weeks

    March - 4.5 weeks

    April - 4.5 weeks

    May - 2 weeks

    This adds up to 40 weeks, but only 9 months.

    It's very strange.

  • Anonymous
    4 years ago

    It is 9 FULL months, month 1 1-4 weeks month 2 5- 8 weeks month 3 9-13 weeks month 4 14-17 weeks month 5 18-22 weeks month 6 23-27 weeks month 7 28 31 weeks month 8 32-35 weeks month 9 36-40 weeks. and also when doctors calculate pregnancy they start from the first day of your last period, most women do not concieve untill 14 days after their last period, and it take 2-3 days for implantion. you are not even pregnant for almost 3 of those 40 weeks.

  • Anonymous
    1 decade ago

    Pregnancy is 10 months girl.

    This is because doctors don't use the regular months like calenders do, for pregnancy doctors rely on the Lunar Calendar, with this calendar months are only 28 days long.

    And I was also born on April 1st, you're friends baby is 7 months old, because he was born at the beginning of a month said month counts in his age. For instance, a baby born on October 1st would be 3 months old on December 1st.

  • Anonymous
    1 decade ago

    Pregnancy is 40 weeks. If you count 4 weeks in a month .. then that is where they get 10 months from.

    But .. there aren't only 4 weeks in every month. Pregnancy is figured on the lunar calendar that is where many people get confused. Better to think of it in just weeks really.. makes it easier.

    Your friends baby is 6 months old. He/She would have been one month old on May 1st, 2 months old on June 1st, 3 months old July 1st... etc...

    She needs to think of April 1st as her baby being 0. Like I said before.. he/she wasn't 1 month old until May 1st.

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  • Froggy
    Lv 4
    1 decade ago

    A pregnancy last a full 9 months so it is more like 10 months. It last 39-40 weeks so that is almost 10 months

  • 1 decade ago

    Because by the time 40 weeks rolls around you have completed 10 months. It's that simple. Take 40 and divide it by 4, what do you get? Ten.

  • 1 decade ago

    It's 10 months because you are counting from the last day of your last period. For example, my last period was Sept 28, 2007. From that date to Oct 28, 2007 is one month pregnant, even though I conceived on October 12, 2007. 10 months from Sept 28, I would have given birth, but my baby was early.

  • Anonymous
    1 decade ago

    I've never heard anyone say that. I always talked about it in weeks when I was pregnant, so it would be more accurate. They can do the math themselves if they want to know how many months it is.


    To the responder ahead of me who said there are 4 weeks in every month ... do you know how many weeks are in a year? 52. Now, take 52 and divide by 12. Does it come out to 4 even? Nope. February is the only month that has exactly 4 weeks in it, and that's only for 3 years out of 4. The rest have 4 weeks plus a fraction. That's why you tell people in weeks instead of months.

  • 1 decade ago

    it lasts for 40 weeks, and they consider a lunar month 4 weeks. therefore, your 40 week pregnancy is 10 lunar months.

  • 1 decade ago

    if you average the days, there are 4 weeks and a few days in a month. since a pregnancy is 40 weeks, that makes 10 months.

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