Baby, Pregnancy, and Parenting Information

A 10 Month Pregnancy?


Is a pregnancy nine months or ten months long? This is a popular pregnancy debate with many women across message boards and in pregnancy communities today. Most people know that a pregnancy consists of the first, second and third trimester. The definition of a trimester is “A period or term of three months”. If this is the case, why do so many people consider themselves pregnant for ten months?  The answer is simple, even if not actually correct. Pregnancies are considered full term at 40 weeks, and many women count four weeks as a month while they are pregnant, making the result a ten month pregnancy. On average there are actually 4.33 weeks in a month, however that a third of a week tends to get lost in the pregnancy shuffle for much of us.

Many women also find it easier, when asked how pregnant they are, to answer in weeks instead of months, because pregnancy is generally a count down. “I am 24 weeks, only 16 weeks to go!” The most general deduction by a bystander would be that the woman is already six months pregnant, when in actuality, per the Gregorian calendar that most of the world lives by, she is only about five and a half months pregnant.

Women who consider themselves 10 months pregnant usually use this form of calculations:

1-4 1
9-12 3
17-20 5
25-28 7
33-36 9

For those that live by the Lunar calendar, this not only makes sense, but is absolutely correct. The Lunar calendar, which is the four weeks it takes for the moon to go from a new moon, to a full moon and back again, would make a pregnancy last for ten months.

For those that live by the Gregorian calendar, and counting by the date you started your last period (let’s say October 15), you would not be one full month pregnant until November 15 and the calculations generally look like this:

November 15 1
January 15 3
March 15 5
May 15 7
July 15 9

However, neither of these calculations is exactly accurate. The most common way to figure out your due date, including the way that most doctors calculate it, is to add nine months and seven days to the start date of your last menstrual period, which would actually be a week before you would have ovulated with a 28-day cycle. Therefore, if you started your LMP on October 15, you due date would be calculated as July 22, not July 15.

November 15 1 4.33
January 15 3 13 (start of second trimester)
March 15 5 21.66
May 15 7 30.33
July 15 9 39

This would make your due date of July 22 be at 40 weeks exactly, or nine months and one week after you started your LMP. This being said, why would someone CHOOSE to be pregnant for ten months?

Another way to look at it is if you consider a pregnancy of 40 weeks to be ten months, and that a year has 52 weeks in it – which you also count four weeks as one month – wouldn’t this mean that your baby would be 13 months old before he turned a year, and you could celebrate his first birthday?

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42 Responses to “A 10 Month Pregnancy?”

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  1. 42
    Timothy Takemoto Says:

    Actually….I am not sure when an egg can be said to be “launched into the womb”. Please will someone tell me? I guess that the progress of the egg from the ovaries to the fallopian tube and then into the womb is fairly analogue and flexible.

    In Japan pregnancy was felt to be 10 months (female body months) and ten days long since the egg was deemed to have been pregnant from the start of the previous period, i.e. when the previous egg made way for the next.

  2. 41
    rachael Says:

    to confused,
    the ultra-sounds def can not always predict ur dates. the bigger the baby gets the more off the ultra-sound are. its actually better to go by the earliest ultra sound dates then the later ones. thats why they change the estimated due dates so much and its y only 4 women out of many actually due give birth around there estimated due date. i can understand fully why people question it even when the ultrasounds give them a date. we know when we had sex. not some machine or doctor does know it better then us actual people who did it lol.

  3. 40
    Calculating Your Due Date | Early Pregnancy | Baby, Pregnancy, and Parenting at Babies Online Says:

    […] account your last period and assume conception took place a week after that date. They then add nine months to that date to give you the estimated due […]

  4. 39
    al r. Says:

    I was in my mother ten months and I have had problems from day one. I am 57 and learned secrets of my own life in the last 10 years. I wish my parents treated me as a child. I complained of pain and they humiliated me.

  5. 38
    uzoma sybil Says:

    A sister was pregnant in April 2008 and gave birth in 13th of March 2009,the child was a still birth.after one week she resumed her normal sexaul life,which resulted in her been pregnant within one month of her last delivery,that is by April 2009 she was pregnant, and she carried the baby to july 2010(15 -16months)can it be possible,bcos the guy who was dating her is in doubt ,to claim the baby.

  6. 37
    sarah Says:

    I’m 30 weeks pregnant due the 9th of june so according to doctors i’m pregnant for 40 weeks = 10 months. what i don’t understand is.. my last period was the 1st of sept till the 7th doctor said i got pregnant the 4th of sept? so i got pregnant while on my period.. i didn’t think this was possible? so i’m very confused.. can anyone help?? i did have sex on the 4th or late night on the 3th..

  7. 36
    erin Says:

    Ok so neyways I’m 7months in 8days can’t wait to meet my lil mann “). Nd yuh do qo up to 10months preqo. Btw; I also h8 how some qirls don’t understand when yur in love yuh don’t wanna ruin whatcha qot. She said she told him b4 he miqht not b tha father of tha baby but he blew it off like she neva said it. So therefore he did that cuz he wants that baby to b his dummy. Jessica keep ya head up mama. Nd forqet tha h8ters they only wanna see yuh fall.

  8. 35
    willams Says:

    can sexly conduct at the time of month of 8

  9. 34
    Confused Says:

    Not sure why so many are stuck on figuring out the date of the last period. When an ultrasound is done, a doctor is able to tell what stage of development the fetus is and go from there.

  10. 33
    Jennifer Says:

    Hi i took a home pregnancy test it came out positive. I had a feeling i was. I was feeling sick. I only had unprotected sex on 1 day which October 6th. I can’t remember when my period was in September. How am i going to now how far and when my due date is?

  11. 32
    Jet Li Says:

    My wife just pass first trimester pregnancy.. We are calculating her due day is around January 5th.. Her LMP was April 1 BUT I think / SURE she got conception (late ovulation) just by the end of April.. It also happened to our first child.. so is there any chance her due date delay by 4 weeks?? say February 5th?? if let’s say by the time of conception/ovulation is like April 28th??

  12. 31
    monica Says:

    I really can’t remember when my last period was.All i know that it was in march,how can i really determinehow far along i am?

  13. 30
    Eve Says:

    I’m still confused here. Tell me because i conceived on the 09 October 2009. How many weeks am i now and when am i due?

  14. 29
    Don't understand dates! - Pregnancy - Second Trimester Forum Says:

    […] 9 months is just a rounded number, its actually closer to 10 months but its easier to say 9 because its easier to seperate it into 3 trimesters this article explains it well…hpregnancy.asp […]

  15. 28
    Sharon Says:

    The women that lie to men about who is the father of their child, makes us Real Woman Look Bad! The child and father diserve to know the truth. Teach your child how to be a liar, great lesson! Why are you having children?

  16. 27
    kt2010 Says:

    Jessica, I feel for you and your situation. I think if we all look at our lives we can all think of a time where we were just out of a relationship, very vulnerable and ended up doing something we regretted later on. However, in your situation now you have to wonder if that small slip in the summer resulted in a lifelong biologic conundrum with this deadbeat being the father. However, when I look at your dates I think there is a very good chance that your ex is the father even though there is still a chance of it being guy #2. You seriously cannot go by the length of your relationship with your ex and the fact that you never got pregnant until you were also with another man. It is almost impossible for our bodies to get pregnant even under good circumstances on a regular many things have to happen at the right time and even then pregnancy may not always occur. It just leads us to remember what a true miracle each pregnancy and each baby really is!! The real truth of it all is.. You ONLY have a 12-24 hour window to get pregnant every month of a normal cycle. Depending on the length of your cycle that 12-24 hour time frame of becoming pregnant usually can happen on the 14th-15th day after your Last Menstrual Period. They say that for people who want to become pregnant should have sex everyday from the 12th to 18th day after the day of their last menstrual period just to be the case they ovulate earlier/later than usual. But it is good to count down to the 14th-15th day from your last mentrual period..then really examine the fact that sperm can live in the body for 2-4 days and try to figure out who you were with exactly when were with each guy. From what you said it sounds like it would be your ex. I hope this helps you.

  17. 26
    LCMelbourne Says:

    At 40 weeks you are 9 1/2 months pregnant you are not 10 months pregnant but you are in your 10th month.

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