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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 September 25th, 2015.

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

favorite movie about anyone having a baby

Sat Nov 29 4:31 AM by Sonic# in Pregnancy & Parenting

When I was little I was wild about Look Who's Talking. I think the novelty of a narrating baby wore off sometime after I saw Milo and Otis.


Babyproofing the House

Sat Nov 29 2:53 AM by rowan in Pregnancy & Parenting

Depends on the dog, tbh. Some get jealous. But yeah a lot of dogs are all like OMG BABIEZ!!


going public with the new pregnancy & parenting forum

Fri Nov 28 7:03 PM by rowan in Pregnancy & Parenting

OMG AKA_LAURA CONGRATULATIONS!


Christmas gifts for small children

Fri Nov 28 4:18 AM by aka_laura in Pregnancy & Parenting

My baby needs diapers, since pooping is currently her favorite activity. An 18 month old in no way needs $2000 worth of gifts.

For older kiddos, I kind of like the "something you want, something you need, something to wear and something to read" thing. It's cheesy, but helps focus the holiday a bit.

I also like books, because I feel like someone really can't have too many books. They're easy to store, good for baby brains, and make good donation items if you do end up with a surplus.


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.


Food restrictions in pregnancy

Sat Nov 29 3:14 AM by Gnarlbanya in Pregnancy & Parenting

Thanks for all the advice, everyone. I'll happily continue with my peanut butter habit, then. In fact the 2 countries with the lowest incidence of peanut allergies are Israel and India, where children are given peanut based foods as some of their first foods. I suspected this might be the case given that food allergies seem to be more prevalent in western societies.

I've looked into the mercury /fish thing a little more (thanks for the Monterey Bay Aquariam recommendation, Rowan) and the rule of thumb seems to be that if the fish is (1) large, (2) predatory and (3) fairly long lived, it will contain more mercury. This is why the advice I'd found on tuna seemed contradictory - some species of tuna (Bluefin, for example) are much bigger than others. Canned tuna is generally smaller fish as big tuna sell whole for serious $. Smaller fish and freshwater fish are pretty much ok. I think it's much easier to know the reasons why some foods are more risky than others as this is easier to remember than an exhaustive list of exclusions.


My brief opinion on Ferguson and all that

Sat Nov 29 1:16 AM by Dawn?Quixotic in Random Weirdos

The also tough thing about these kind of riots is, how many are out there starting out as peaceful protesters, and how many don't care about that but are part of it anyway?

I remember people were pointing out about looting and stuff and how that's not a good response, but the people doing that weren't the protesters.


Finding out baby's sex before birth

Fri Nov 28 7:02 PM by rowan in Pregnancy & Parenting

We also opted not to tell our family the sex of our baby before she was born. We had decided not to do the blood tests or anything (our insurance also would have covered it), and on the ultrasound she was REALLY uncooperative anyway, so when the tech asked if we wanted to know, we said "not really" and she looked really relieved and said "Good because I really can't tell and if you don't want to know we can stop now". So it was good for us that she was uncooperative. :) We still got a lot of pressure but living far from family made at least that easier.

I think I've mentioned my mom is awesome. She ran a bunch of interference for us and made people not bother me too much (I have plenty of nurses in my family, which means they know I could go back in and find out if I'd wanted).

So we got a lot of yellow and green (and some blue, and I made sure to buy pink because it's stupid girls can wear blue and boys "can't" wear pink) for the baby showers. Once she was born, we get more pink, but since most of the people who buy her things are Grandma and Grandpa and Auntie and Uncle, and they get it, they also get her other colors too.


how can we spread the word on the touching thing?

Wed Nov 26 8:02 PM by melsbells in Pregnancy & Parenting

I almost never had to deal with this. I was living in a remote area and not interacting much with others. Also, the culture here doesn't seem conducive of interacting with people by touching them.

One of my spouse's young nieces touched my belly and I didn't know how to tell her not to do it. She was immediately corrected by her mother about not touching people without permission.

Then my parents arrived. I mostly just dealt with their touch, but probably not with much class.


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.


Pregnancy Books

Sat Nov 29 2:58 AM by rowan in Pregnancy & Parenting

Back when I was pregnant I read a lot of things. I truly hated the "what to expect" books because they seemed really demeaning to the dad (though i do have on friend who's husband is like that and needs to be cajoled kicking and screaming into helping, sigh). I really liked the Dr. Sears "Pregnancy" book and also the one that goes up to age two. Unfortunately the Sears' have gone off the weird end, so that kind of makes me hesitant to even recommend that much. (Some people read more into that book about shaming if you don't breastfeed; I didn't get that out of that, I thought they were like here's the benefits, here are some things to help you out but in the end if you can't that's ok. Just if you're going bottle you don't need as much advice, right?)

That was a while ago, though. What books are out now that are good and not enraging? Or which ones should be avoided?


Hello friends!

Fri Nov 28 7:36 PM by rowan in Random Weirdos

Yay aka_laura's back!

And she's also my niece's mom!
waaaaaaait, what? O.o


pick an art museum

Fri Nov 28 6:52 AM by Meperidine in Random Weirdos

I got a comped ticket to the MoMA once when a friend worked there. I only had two hours to spend there, but easily could've spent 6. I don't think of museum-going as a particular interest of mine, but I was sucked into something new in every room. I haven't gone back, but I'd love to.

My parents dragged my sister and me to see "Carnation, Lily, Lily, Rose" and "Sunday in the Park" at the Chicago Art Institute when we were small. We didn't get there til near closing time, so we had to book it through the entire museum to get there for a few minutes' viewing, and we were tired and complained the whole time because we were children and jerks, but I admit I won't forget the paintings. Our parents cooed over the fact that the girls in "Carnation" could've been us, and the whole pointillism thing very much impressed me.


dealbreaker opinions

Wed Nov 26 5:29 PM by Storage and Disposal in Random Weirdos

really you guys? I unfriend all the time!

why mute someone? that means they're still going to be seeing your posts, commenting on your photos, getting to be "in" your life, and never know anything changed. what good is happening by keeping them around?

My former art teacher is quite conservative, but I still like his comments on my artwork.

I put people I think are otherwise perfectly delightful on mute because they flood facebook with useless crap. I don't want them to get the idea that I hate them, but I don't feel like seeing pages of what they have to say.

I think a lot of people have opinions I don't care for. Rather than offending someone I know and respect in person, I choose to just not see it. Facebook has a knack for showing sides of people I don't want to see, but it's just small sides of them. To me, it's not worth shutting out the person completely. After awhile, I occasionally take them off mute to see if they stopped with their nonsense.


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