Ten Months Pregnant (?)

The subject of due dates and the length of pregnancy is one that is often debated! Some women seem to want the badge of “longest pregnancy”, others want to know how soon they might be able to see baby this side of the womb. Guest author Heather {mother of three young children (Ellie, Max, and Dot) from Indianapolis, Indiana.}, gives us her perspective.

Doesn’t 40 Weeks Equal 10 Months?

Pregnancies are measured in weeks starting with the first day of a woman’s last period, with a 40-week duration, which is the due date. Pregnancies are still 9 months, actually a little less, just like they’ve always been.

40 weeks x 7 days =280 days – 14 days (day 1 through conception*) = 266 days / 30.5 days per month = 8.72 months

*I guess, in order to have a common starting point to begin measuring pregnancies for all women, doctors chose to start the pregnancy clock on the first day of a woman’s last period, even though this day is roughly 14 days before ovulation/conception.

And, as you can see by any kitchen calendar, months are not 4 weeks long. Most are 30-31 days. Herein lies the confusion.

So, one of my little pet peeves is when someone tells me how many months along they are, based on the number of weeks, divided by four… that they are 6 months pregnant (24 weeks) or 8 months pregnant (32 weeks), or when they tell you, “it turns out that pregnancies are actually 10 months.” I knew a woman who kept saying she was 7 ½ months pregnant when she had 10 weeks left. So, naturally, everyone thought she looked great, and she did, but she was only 6 ½ months pregnant.

So How Should I Calculate My Pregnancy?

Let’s look at one pregnancy example. If the first day of your last period was December 13th, your due date would be September 20th. There are a couple of different ways you can tell people how many months along you are, if you prefer to think of pregnancies in terms of “months.”

The simplest way would be to take your due date and subtract months (not weeks) from it. In the above example, your due date is September 20th, so you would be 8 months pregnant on August 20th, 7 months pregnant on July 20th, 6 months pregnant on June 20th, etc.

The other way to tell people how many months along you are is to start from two weeks into the pregnancy clock (December 27th), then add months by 30 days, not 4 weeks. So, January 27th would make 1 month, February 27th would make 2 months, etc.

Both offer up a “close enough” answer for those asking.

Does It Really Matter?

I’ve been told on more than one occasion that I analyze too much, which is probably very obvious by my post. Yes, I tend to over-think things. Most people might not care if you mess up on your calculation or interpretation of your pregnancy dates. But many people still want to know how far along you are in terms of months, especially if they are not familiar with the “weeks” method. You might see a look of confusion on their faces when you tell them how many weeks-along you are.

But in the end, it’s still a beautiful, precious baby…that probably won’t come on his or her due date anyway.


People ask a lot of questions to pregnant women! Do you tell people how many ‘weeks’ pregnant you are, or do you go by “months”?

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About donielle

Donielle is a natural momma of two, lover of real foods, and owner and editor of Grand Rapids Natural Living and Naturally Knocked Up. You can usually find her in the kitchen whipping up some nourishing foods, cuddled on the couch reading books to the littles, avoiding the laundry and Mt. Saint Dishes, or tapping away on the laptop. Her husband puts up with her sometimes crazy "hippie" ways, but loves her regardless. Welcome to my home away from home.


  1. I’m an over-analyzer as well, and this has always driven me nuts too! I’m with you…count backward from the end, or divide the weeks by 4.5 (it’s a rough estimate, but it’s closer than dividing by 4!).

  2. Thanks for this informative analysis! A lady told me once that pregnancy is 10 months long and I never could figure out what the heck she was talking about! Now I realize where she was coming from… and that she was dead wrong, lol. For me weeks was always easier than months; and I found that women in my generation were OK with that and that’s actually the number they wanted to know. Women in my mom’s generation wanted to know months, so I would generally just count from the month I got pregnant, but it makes more sense to count backwards.

  3. Totally hear you. I’ve also resorted to the EDD-minus-what’s-left calculation, for people who don’t process the “weeks” part so easily. (Sometimes just “a couple months left,” if I’m feeling vague; a lot of the time, the people pushing for a months number are trying to compare with how they/others looked at that number of months, which irritates me beyond any rational measure when I’m pregnant.)

    Of course, I generally give a 2-week range and add “-ish” to the weeks, anyway, since I want to be very clear that I’m not holding Baby to a deadline, LOL… I’m afraid I may be giving the impression that we don’t *know* how long Baby’s been growing, when the exact opposite is the case. But ah, well. Most people are just happy with “Baby’s probably arriving around the earlier half/latter half/middle of X month,” when that’s what they really wanted to know. 🙂

  4. Oh so funny! I’ve had two kids and have never given it much thought! I just kind of round to the nearest month (I guess I count months backwards from the EDD — keeping to the nine months). I’ve found that people ask most during the last couple of months — so I just given then a rough due date — end of July!

  5. Since I’ve never been pregnant, I’ve never been that “in-tune” with the whole weeks concept, although I realize many expecting mothers calculate their pregnancy that way. Unless I’m reminded, I don’t even know how many weeks a pregnancy is suppose to be – LOL… I try not to have a look of “duhhh… okay… so you’re 30 weeks along. Does that mean you’re due any day now?” (I got straight A’s in college math classes, but you’d never know it in my day to day calculating).

    This is a great post and apparently one MANY can relate to. 🙂