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Pregnancy Due Date Ranges

This table attempts to estimate your probability of going into labor on different individual days based on your estimated due date. If you don't know your due date, or just want a handy daily page to tell you where you're at, use the pregnancy calendar.

It's based on the idea that the average pregnancy lasts 40 weeks with a standard deviation of about 10 days. This means you're more likely to go into labor on one of the days close to your due date. For instance, about half of all babies are born within a week of their date. Scroll to the bottom of this page if you want to know more about where I got these numbers.

The following dates are based on an estimated due date of December 20th, 2014.

Change due date:
Month Day Year
Date Progress Overall probability of
spontaneous labor
Current probability of
spontaneous labor
probability of a pregnant woman at this stage going into labor
On this date By this date On this date By this date On this date Within 3 days Within 5 days Within 7 days
Saturday November 15th, 2014 35W, 0D 0.01% 0.02% -% -% -% 0.1% 0.1% 0.2%
Sunday November 16th, 2014 35W, 1D 0.01% 0.03% -% -% -% 0.1% 0.2% 0.3%
Monday November 17th, 2014 35W, 2D 0.02% 0.05% -% -% -% 0.1% 0.2% 0.4%
Tuesday November 18th, 2014 35W, 3D 0.02% 0.07% -% -% -% 0.1% 0.3% 0.6%
Wednesday November 19th, 2014 35W, 4D 0.03% 0.1% -% -% -% 0.2% 0.4% 0.7%
Thursday November 20th, 2014 35W, 5D 0.04% 0.13% -% -% -% 0.2% 0.5% 0.9%
Friday November 21st, 2014 35W, 6D 0.06% 0.19% -% -% 0.1% 0.3% 0.6% 1.2%
Saturday November 22nd, 2014 36W, 0D 0.08% 0.26% -% -% 0.1% 0.4% 0.8% 1.5%
Sunday November 23rd, 2014 36W, 1D 0.1% 0.35% -% -% 0.1% 0.5% 1% 1.9%
Monday November 24th, 2014 36W, 2D 0.14% 0.47% -% -% 0.1% 0.6% 1.3% 2.4%
Tuesday November 25th, 2014 36W, 3D 0.18% 0.62% -% -% 0.2% 0.8% 1.7% 3%
Wednesday November 26th, 2014 36W, 4D 0.22% 0.82% -% -% 0.2% 1% 2.1% 3.7%
Thursday November 27th, 2014 36W, 5D 0.28% 1.07% 0.3% 0.3% 0.3% 1.2% 2.5% 4.5%
Friday November 28th, 2014 36W, 6D 0.35% 1.39% 0.4% 0.6% 0.4% 1.5% 3.1% 5.4%
Saturday November 29th, 2014 37W, 0D 0.44% 1.79% 0.4% 1% 0.4% 1.8% 3.8% 6.4%
Sunday November 30th, 2014 37W, 1D 0.54% 2.28% 0.5% 1.5% 0.6% 2.2% 4.5% 7.6%
Monday December 1st, 2014 37W, 2D 0.66% 2.87% 0.7% 2.1% 0.7% 2.7% 5.4% 8.9%
Tuesday December 2nd, 2014 37W, 3D 0.79% 3.59% 0.8% 2.8% 0.8% 3.2% 6.3% 10.4%
Wednesday December 3rd, 2014 37W, 4D 0.94% 4.46% 0.9% 3.7% 1% 3.8% 7.4% 11.9%
Thursday December 4th, 2014 37W, 5D 1.11% 5.48% 1.1% 4.7% 1.2% 4.4% 8.6% 13.7%
Friday December 5th, 2014 37W, 6D 1.3% 6.68% 1.3% 5.9% 1.4% 5.2% 9.8% 15.5%
Saturday December 6th, 2014 38W, 0D 1.5% 8.08% 1.5% 7.3% 1.6% 6% 11.2% 17.5%
Sunday December 7th, 2014 38W, 1D 1.71% 9.68% 1.7% 8.9% 1.9% 6.9% 12.7% 19.7%
Monday December 8th, 2014 38W, 2D 1.94% 11.51% 2% 10.8% 2.2% 7.8% 14.3% 21.9%
Tuesday December 9th, 2014 38W, 3D 2.18% 13.57% 2.2% 12.9% 2.5% 8.8% 16% 24.2%
Wednesday December 10th, 2014 38W, 4D 2.42% 15.87% 2.4% 15.2% 2.9% 9.9% 17.8% 26.6%
Thursday December 11th, 2014 38W, 5D 2.66% 18.41% 2.7% 17.7% 3.3% 11.1% 19.7% 29%
Friday December 12th, 2014 38W, 6D 2.9% 21.19% 2.9% 20.5% 3.7% 12.3% 21.6% 31.5%
Saturday December 13th, 2014 39W, 0D 3.12% 24.2% 3.1% 23.6% 4.1% 13.5% 23.6% 34%
Sunday December 14th, 2014 39W, 1D 3.33% 27.43% 3.4% 26.8% 4.6% 14.9% 25.6% 36.6%
Monday December 15th, 2014 39W, 2D 3.52% 30.85% 3.5% 30.3% 5.1% 16.2% 27.7% 39.2%
Tuesday December 16th, 2014 39W, 3D 3.68% 34.46% 3.7% 33.9% 5.6% 17.6% 29.8% 41.7%
Wednesday December 17th, 2014 39W, 4D 3.81% 38.21% 3.8% 37.7% 6.2% 19.1% 31.9% 44.2%
Thursday December 18th, 2014 39W, 5D 3.91% 42.07% 3.9% 41.6% 6.7% 20.6% 34% 46.7%
Friday December 19th, 2014 39W, 6D 3.97% 46.02% 4% 45.6% 7.4% 22.1% 36.2% 49.2%
Saturday December 20th, 2014 40W, 0D 3.99% 50% 4% 49.6% 8% 23.6% 38.3% 51.6%
Sunday December 21st, 2014 40W, 1D 3.97% 53.98% 4% 53.6% 8.6% 25.1% 40.4% 54%
Monday December 22nd, 2014 40W, 2D 3.91% 57.93% 3.9% 57.6% 9.3% 26.7% 42.5% 56.2%
Tuesday December 23rd, 2014 40W, 3D 3.81% 61.79% 3.8% 61.5% 10% 28.2% 44.5% 58.5%
Wednesday December 24th, 2014 40W, 4D 3.68% 65.54% 3.7% 65.3% 10.7% 29.8% 46.6% 60.6%
Thursday December 25th, 2014 40W, 5D 3.52% 69.15% 3.5% 68.9% 11.4% 31.3% 48.6% 62.7%
Friday December 26th, 2014 40W, 6D 3.33% 72.57% 3.4% 72.3% 12.1% 32.9% 50.5% 64.7%
Saturday December 27th, 2014 41W, 0D 3.12% 75.8% 3.1% 75.6% 12.9% 34.4% 52.4% 66.6%
Sunday December 28th, 2014 41W, 1D 2.9% 78.81% 2.9% 78.6% 13.7% 36% 54.3% 68.5%
Monday December 29th, 2014 41W, 2D 2.66% 81.59% 2.7% 81.4% 14.4% 37.5% 56.1% 70.2%
Tuesday December 30th, 2014 41W, 3D 2.42% 84.13% 2.4% 84% 15.2% 39% 57.9% 71.9%
Wednesday December 31st, 2014 41W, 4D 2.18% 86.43% 2.2% 86.3% 16.1% 40.5% 59.6% 73.5%
Thursday January 1st, 2015 41W, 5D 1.94% 88.49% 2% 88.4% 16.9% 42% 61.3% 75.1%
Friday January 2nd, 2015 41W, 6D 1.71% 90.32% 1.7% 90.2% 17.7% 43.4% 62.9% 76.4%
Saturday January 3rd, 2015 42W, 0D 1.5% 91.92% 1.5% 91.9% 18.6% 44.8% 64.5% 77.8%
Sunday January 4th, 2015 42W, 1D 1.3% 93.32% 1.3% 93.3% 19.5% 46.3% 65.9% 79.2%
Monday January 5th, 2015 42W, 2D 1.11% 94.52% 1.1% 94.5% 20.3% 47.6% 67.3% 80.5%
Tuesday January 6th, 2015 42W, 3D 0.94% 95.54% 0.9% 95.5% 21.1% 48.9% 68.8% 81.6%
Wednesday January 7th, 2015 42W, 4D 0.79% 96.41% 0.8% 96.4% 22% 50.1% 70.2% 82.7%
Thursday January 8th, 2015 42W, 5D 0.66% 97.13% 0.7% 97.1% 23% 51.6% 71.4% 83.6%
Friday January 9th, 2015 42W, 6D 0.54% 97.72% 0.5% 97.7% 23.7% 53.1% 72.8% 84.6%
Saturday January 10th, 2015 43W, 0D 0.44% 98.21% 0.4% 98.2% 24.6% 54.2% 73.7% 85.5%
Sunday January 11th, 2015 43W, 1D 0.35% 98.61% 0.4% 98.6% 25.2% 55.4% 74.8% 86.3%
Monday January 12th, 2015 43W, 2D 0.28% 98.93% 0.3% 98.9% 26.2% 56.1% 75.7% 87.9%
Tuesday January 13th, 2015 43W, 3D 0.22% 99.18% 0.2% 99.2% 26.8% 57.3% 76.8% -%
Wednesday January 14th, 2015 43W, 4D 0.18% 99.38% 0.2% 99.4% 29% 58.1% 79% -%
Thursday January 15th, 2015 43W, 5D 0.14% 99.53% 0.1% 99.5% 29.8% 59.6% -% -%
Friday January 16th, 2015 43W, 6D 0.1% 99.65% 0.1% 99.6% 28.6% 62.9% -% -%
Saturday January 17th, 2015 44W, 0D 0.08% 99.74% 0.1% 99.7% 30.8% -% -% -%
Sunday January 18th, 2015 44W, 1D 0.06% 99.81% 0.1% 99.8% 31.6% -% -% -%
Monday January 19th, 2015 44W, 2D 0.04% 99.87% 0% 99.9% 30.8% -% -% -%

Probability of labor on a given day

Probability of labor by a given day

Notes and disclaimers

All percentages are estimates based on mathematical averages and should not be taken terribly seriously... just because you only have 5% chance of going into labor two weeks early, that doesn't mean you should schedule a trip to the bahamas that weekend (see xkcd to get what I mean here).

You should (obviously) listen to your doctor or midwife on all matters related to pregnancy and childbirth. Just because this chart tells you that a 42W pregnant woman has a high chance of delivering in the next seven days, it doesn't mean it's healthy for her to be pregnant for seven more days. If your doctor wants to increase probability of delivery by inducing labor, there's probably a good reason.

Finding good distribution statistics on spontaneous labor is interesting. I have not found a study with an exact daily breakdown of when babies are born. However I have read way too much on this topic, so I can tell you that my favorite published research is The length of human pregnancy as calculated by ultrasonographic measurement of the fetal biparietal diameter (H. Kieler, O. Axelsson, S. Nilsson, U. Waldenströ) which a very nice table of 10 published studies, which found various means between 272-283 days. The study contributes their own results as well, analyzing nearly 2000 mothers who went into labor spontaneously, and there's graphs of what they found. They found a mean around 280 days, and standard deviations between 8-11 days. There's a big list of other studies and answers in the Introduction to my due date survey results.

Which leads to this topic... I am also in the process of collecting my own statistics. If you have had a baby, please take my due date survey. Oddly enough, the numbers I've collected so far support my messy hunch that pregnancy length has a 40-week mean and 9-10 day standard deviation. So go me.

Anyway if you have better research, drop me an e-mail (spacefem@spacefem.com).

Charts are generated by flot.

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Recent Comments

For more support, encouragement, Q&A, you are invited to join our pregnancy forum. We are dedicated to answering complicated questions as logically as we possibly can.

Which stereotypes do you completely shatter?

Wed Nov 26 3:46 PM by C-3PO in Random Weirdos

I'm male, but I'm 5'6", I don't like sports, I'm asexual, I have a lousy sense of direction, and I struggle with Mathematics.

I'm from Texas, but I take public transportation, speak English correctly, tend towards agnosticism, and dislike competitive attitudes.

I'm white, but my family isn't wealthy or educated. (I actually kind of wish I fit this one.)


going public with the new pregnancy & parenting forum

Wed Nov 26 9:53 AM by spacefem in Pregnancy & Parenting

I started up this forum very recently - was going to give it some time to flesh out before I announced it to the world but what the heck, let's jump in the deep end.

I wanted to start our own pregnancy forum for several reasons:

- This site is frequented by smarter-than-average, geeky pregnant women looking up statistics, and I think you'd be nice to talk to more.

- I get the nicest emails from visitors and I think it's a shame that I'm the only one who gets to read your feedback.

- The world deserves a pregnancy forum that is not pink.

- The world deserves a pregnancy forum that is not smothered with ads for formula, stretch mark creams, and weight loss ads about "getting your body back"

- Several of us on spacefem.com are parents and might have some good advice to give. It's still kinda early to tell if I've screwed up my kids, but I'm optimistic.

how about it, pregnant lurkers? is this the kind of place where you could come in and say hi?


Christmas gifts for small children

Wed Nov 26 2:13 AM by spacefem in Pregnancy & Parenting

So I realize we should celebrate all that we have, but I was a bit surprised that someone in my babycenter month community plans to spend $2000, so far, on christmas presents for her 18-month-old:
http://community.babycenter.com/post/a5 ... or_lo_poll

my child basically wants to go through the trash, she's happy with cardboard boxes, am I the only one who wants to keep Christmas a little downplayed at this age?

last year we wrapped up a hand-me-down baby toy that my oldest had forgotten about, just so the older kid would see her little sister get a gift. we spend $0. this year I may dramatically increase this by getting her some clothes.

bigger kids get more fun to buy for - but even then, it's weird for me to see four-year-olds getting their own ipads, right?

what's your shopping list look like this year? how do you keep it under control?


What's up?

Mon Nov 24 9:26 PM by DWH in Random Weirdos

Yooooooooooooooooo I keep forgetting to tell you I'm in LA until next Saturday and we should grab lunch if you're free!

Wait whaaaaaaaaaat, okay, I'm leaving town tomorrow for Thanksgiving but I'm going to move this discussion to Facebook.

And MFS, of course you should be scared. BAHAHAHAHA


books vs. movies the showdown!

Mon Nov 17 6:49 PM by Sonic# in Random Weirdos

Sometimes I try to see whether the film and the book each stand on their own. If they both do, I don't worry as much about which is better.

When I like the book more: usually it has to do with being so in love with the worldcraft and the descriptions of the book that the film can be entertaining and even moving but just doesn't have the form to develop those things I otherwise loved. See LOTR books (loooove) v. films (love). Sometimes the books are just better, usually because they're in the hands of an author much better than anything the film produced - see Fantastic Voyage by Isaac Asimov, or Dune compared even to David Lynch's version, or the ill-fated attempt to make an Earthsea miniseries.

When I like the film more: when there's something to the film that is brilliant and well-done in its own light. If I come away from the film really liking it, and think the book adds some things but isn't necessary, I like the film more. I'm thinking of Howl's Moving Castle as a good example, since I like the books but love even more its combination with Miyazaki's animation style and storytelling. This also goes for a lot of films that are novelized, like Star Wars. And sorry to the book The Princess Bride, but the film is the first to come to mind.


forum suggestion box

Wed Nov 26 2:12 PM by spacefem in Random Weirdos

spoooooooon!

I fixed the chat pages, sorcery does have a web-based client that's working. next chat day is tuesday!

I forwarded the whole /chat to the wiki so we have one place to edit.


favorite movie about anyone having a baby

Wed Nov 26 4:41 AM by cwbyrvr in Pregnancy & Parenting

I voted for Juno just before I realized that Saved was an option. I like both, but I'd have to say I like Saved more.


Code-meshing

Wed Nov 26 1:57 AM by Sonic# in Random Weirdos

First, humor me a bit. You see the word code-meshing. What do you think of?
I initially thought of some sort of script that recognizes multiple computer programing languages. So the term is new to me and has led me to more questions.

I have Appalacian English influences that come up in my speech at times without my notice. Then I have British English influence, but it only creeps into my spelling. With Appalacian English, I can seperate out what's "wrong" if asked, but I don't do so well categorizing my American spelling and British spelling. Does code-meshing need to be intentional?

Both questions are excellent. This first one I've been talking through a lot with my staff group. Our answer is that it doesn't have to be intentional, but by practicing it we might become more effective at code-meshing. In that way, it is a little like creative writing, where over time all of the genres and elements of writing you've been practicing come out in new and sometimes unanticipated ways. Of course we mix elements of different forms of speech, elements of genres, sayings and metaphors in our own idiolect (the way each individual speaks); practicing particular points of that mixture enriches what we can do there.


organizing

Fri Nov 21 6:37 AM by Storage and Disposal in Random Weirdos

I'm rarely in the mood to organize, but when I do it's really gratifying. The biggest thing is DVD's since I have like a thousand. Last time we organized it, we did so by color. I'm not sure what I'll do next.

The rest of the apartment could definitely use some organizing, but that's less fun.


stars by your name

Sat Nov 15 7:20 PM by rowan in Random Weirdos

*nibbles purple stars*


dealbreaker opinions

Wed Nov 26 10:00 AM by Dawn?Quixotic in Random Weirdos

I don't mind people being ignorant, until you point stuff out.
I flipped out on this guy when he said my theoretical description of a "berserker attacking people with his bare hands" (in the theoretical case it might be okay to pull your gun on someone who wasn't armed) that this described Michael Brown "to a tee".
Same deal with the case of the cosplayer who was murdered and supposedly was swinging the sword at people.
Probably didn't happen.
Do you seriously believe the media? The police? Would you believe anyone else accused of murder if they made up these excuses?
But forget eyewitnesses that say he wasn't doing anything.
We only want the witness that hate black people and will lie/misremember to suit their narrative.


calling obama a worthless moron

Sometimes these days I dunno how far off this is. I wasn't really amused by his response to Ferguson, but I suppose it was the "presidential" thing to say.


how can we spread the word on the touching thing?

Wed Nov 26 2:14 AM by spacefem in Pregnancy & Parenting

did anyone else have to deal with touchy people during their pregnancy? 'cause I did!

and I know they were well-meaning but it was WEIRD, and doubly weird when they'd ask "how's that baby!" and I... had no great response. good I guess? been a while since I called it on the phone?

why do people think it's okay to randomly feel you? and good snarky responses you found that made it stop? or did you just learn to deal?


Profile updates

Tue Nov 25 4:17 AM by cwbyrvr in Random Weirdos

My occupation used to be "college student/bum" which made it an interesting answer to what I wanted to be when I grew up for sure. Glad to see I wasn't the only one. I changed it, but I already forget what to... probably that I still don't know.


Are you prepared?

Thu Nov 20 12:25 PM by Aelwyn in Random Weirdos

No, not at all. I have nothing stocked in my place.
However I do live less than 2 minutes from a subway which doubles up as a bomb shelter. Handy.


when do you have to introvert?

Wed Nov 12 8:33 PM by melsbells in Random Weirdos

I've had a bit of the opposite reversal of Meperidine. I have always been extremely introverted, but for the past two years I have grown to crave social contact. My spouse is the most introverted person I have ever encountered and my primary social outlet. I think he'd like me to make friends just so I'll leave him alone sometimes. I'm in a class to learn the language now and sometimes I think I could be friends with one of the other foreigners. We can barely communicate with each other, but my current standards for friends-in-the-flesh are fairly low.