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, 2016.

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
Sunday August 21st, 2016 35W, 0D 0.01% 0.02% -% -% -% 0.1% 0.1% 0.2%
Monday August 22nd, 2016 35W, 1D 0.01% 0.03% -% -% -% 0.1% 0.2% 0.3%
Tuesday August 23rd, 2016 35W, 2D 0.02% 0.05% -% -% -% 0.1% 0.2% 0.4%
Wednesday August 24th, 2016 35W, 3D 0.02% 0.07% -% -% -% 0.1% 0.3% 0.6%
Thursday August 25th, 2016 35W, 4D 0.03% 0.1% -% -% -% 0.2% 0.4% 0.7%
Friday August 26th, 2016 35W, 5D 0.04% 0.13% -% -% -% 0.2% 0.5% 0.9%
Saturday August 27th, 2016 35W, 6D 0.06% 0.19% -% -% 0.1% 0.3% 0.6% 1.2%
Sunday August 28th, 2016 36W, 0D 0.08% 0.26% -% -% 0.1% 0.4% 0.8% 1.5%
Monday August 29th, 2016 36W, 1D 0.1% 0.35% -% -% 0.1% 0.5% 1% 1.9%
Tuesday August 30th, 2016 36W, 2D 0.14% 0.47% -% -% 0.1% 0.6% 1.3% 2.4%
Wednesday August 31st, 2016 36W, 3D 0.18% 0.62% -% -% 0.2% 0.8% 1.7% 3%
Thursday September 1st, 2016 36W, 4D 0.22% 0.82% -% -% 0.2% 1% 2.1% 3.7%
Friday September 2nd, 2016 36W, 5D 0.28% 1.07% -% -% 0.3% 1.2% 2.5% 4.5%
Saturday September 3rd, 2016 36W, 6D 0.35% 1.39% -% -% 0.4% 1.5% 3.1% 5.4%
Sunday September 4th, 2016 37W, 0D 0.44% 1.79% -% -% 0.4% 1.8% 3.8% 6.4%
Monday September 5th, 2016 37W, 1D 0.54% 2.28% -% -% 0.6% 2.2% 4.5% 7.6%
Tuesday September 6th, 2016 37W, 2D 0.66% 2.87% -% -% 0.7% 2.7% 5.4% 8.9%
Wednesday September 7th, 2016 37W, 3D 0.79% 3.59% -% -% 0.8% 3.2% 6.3% 10.4%
Thursday September 8th, 2016 37W, 4D 0.94% 4.46% -% -% 1% 3.8% 7.4% 11.9%
Friday September 9th, 2016 37W, 5D 1.11% 5.48% -% -% 1.2% 4.4% 8.6% 13.7%
Saturday September 10th, 2016 37W, 6D 1.3% 6.68% -% -% 1.4% 5.2% 9.8% 15.5%
Sunday September 11th, 2016 38W, 0D 1.5% 8.08% -% -% 1.6% 6% 11.2% 17.5%
Monday September 12th, 2016 38W, 1D 1.71% 9.68% -% -% 1.9% 6.9% 12.7% 19.7%
Tuesday September 13th, 2016 38W, 2D 1.94% 11.51% -% -% 2.2% 7.8% 14.3% 21.9%
Wednesday September 14th, 2016 38W, 3D 2.18% 13.57% -% -% 2.5% 8.8% 16% 24.2%
Thursday September 15th, 2016 38W, 4D 2.42% 15.87% -% -% 2.9% 9.9% 17.8% 26.6%
Friday September 16th, 2016 38W, 5D 2.66% 18.41% -% -% 3.3% 11.1% 19.7% 29%
Saturday September 17th, 2016 38W, 6D 2.9% 21.19% -% -% 3.7% 12.3% 21.6% 31.5%
Sunday September 18th, 2016 39W, 0D 3.12% 24.2% -% -% 4.1% 13.5% 23.6% 34%
Monday September 19th, 2016 39W, 1D 3.33% 27.43% -% -% 4.6% 14.9% 25.6% 36.6%
Tuesday September 20th, 2016 39W, 2D 3.52% 30.85% -% -% 5.1% 16.2% 27.7% 39.2%
Wednesday September 21st, 2016 39W, 3D 3.68% 34.46% -% -% 5.6% 17.6% 29.8% 41.7%
Thursday September 22nd, 2016 39W, 4D 3.81% 38.21% -% -% 6.2% 19.1% 31.9% 44.2%
Friday September 23rd, 2016 39W, 5D 3.91% 42.07% -% -% 6.7% 20.6% 34% 46.7%
Saturday September 24th, 2016 39W, 6D 3.97% 46.02% -% -% 7.4% 22.1% 36.2% 49.2%
Sunday September 25th, 2016 40W, 0D 3.99% 50% 8% 0% 8% 23.6% 38.3% 51.6%
Monday September 26th, 2016 40W, 1D 3.97% 53.98% 7.9% 8% 8.6% 25.1% 40.4% 54%
Tuesday September 27th, 2016 40W, 2D 3.91% 57.93% 7.8% 15.9% 9.3% 26.7% 42.5% 56.2%
Wednesday September 28th, 2016 40W, 3D 3.81% 61.79% 7.6% 23.6% 10% 28.2% 44.5% 58.5%
Thursday September 29th, 2016 40W, 4D 3.68% 65.54% 7.4% 31.1% 10.7% 29.8% 46.6% 60.6%
Friday September 30th, 2016 40W, 5D 3.52% 69.15% 7% 38.3% 11.4% 31.3% 48.6% 62.7%
Saturday October 1st, 2016 40W, 6D 3.33% 72.57% 6.7% 45.1% 12.1% 32.9% 50.5% 64.7%
Sunday October 2nd, 2016 41W, 0D 3.12% 75.8% 6.2% 51.6% 12.9% 34.4% 52.4% 66.6%
Monday October 3rd, 2016 41W, 1D 2.9% 78.81% 5.8% 57.6% 13.7% 36% 54.3% 68.5%
Tuesday October 4th, 2016 41W, 2D 2.66% 81.59% 5.3% 63.2% 14.4% 37.5% 56.1% 70.2%
Wednesday October 5th, 2016 41W, 3D 2.42% 84.13% 4.8% 68.3% 15.2% 39% 57.9% 71.9%
Thursday October 6th, 2016 41W, 4D 2.18% 86.43% 4.4% 72.9% 16.1% 40.5% 59.6% 73.5%
Friday October 7th, 2016 41W, 5D 1.94% 88.49% 3.9% 77% 16.9% 42% 61.3% 75.1%
Saturday October 8th, 2016 41W, 6D 1.71% 90.32% 3.4% 80.6% 17.7% 43.4% 62.9% 76.4%
Sunday October 9th, 2016 42W, 0D 1.5% 91.92% 3% 83.8% 18.6% 44.8% 64.5% 77.8%
Monday October 10th, 2016 42W, 1D 1.3% 93.32% 2.6% 86.6% 19.5% 46.3% 65.9% 79.2%
Tuesday October 11th, 2016 42W, 2D 1.11% 94.52% 2.2% 89% 20.3% 47.6% 67.3% 80.5%
Wednesday October 12th, 2016 42W, 3D 0.94% 95.54% 1.9% 91.1% 21.1% 48.9% 68.8% 81.6%
Thursday October 13th, 2016 42W, 4D 0.79% 96.41% 1.6% 92.8% 22% 50.1% 70.2% 82.7%
Friday October 14th, 2016 42W, 5D 0.66% 97.13% 1.3% 94.3% 23% 51.6% 71.4% 83.6%
Saturday October 15th, 2016 42W, 6D 0.54% 97.72% 1.1% 95.4% 23.7% 53.1% 72.8% 84.6%
Sunday October 16th, 2016 43W, 0D 0.44% 98.21% 0.9% 96.4% 24.6% 54.2% 73.7% 85.5%
Monday October 17th, 2016 43W, 1D 0.35% 98.61% 0.7% 97.2% 25.2% 55.4% 74.8% 86.3%
Tuesday October 18th, 2016 43W, 2D 0.28% 98.93% 0.6% 97.9% 26.2% 56.1% 75.7% 87.9%
Wednesday October 19th, 2016 43W, 3D 0.22% 99.18% 0.4% 98.4% 26.8% 57.3% 76.8% -%
Thursday October 20th, 2016 43W, 4D 0.18% 99.38% 0.4% 98.8% 29% 58.1% 79% -%
Friday October 21st, 2016 43W, 5D 0.14% 99.53% 0.3% 99.1% 29.8% 59.6% -% -%
Saturday October 22nd, 2016 43W, 6D 0.1% 99.65% 0.2% 99.3% 28.6% 62.9% -% -%
Sunday October 23rd, 2016 44W, 0D 0.08% 99.74% 0.2% 99.5% 30.8% -% -% -%
Monday October 24th, 2016 44W, 1D 0.06% 99.81% 0.1% 99.6% 31.6% -% -% -%
Tuesday October 25th, 2016 44W, 2D 0.04% 99.87% 0.1% 99.7% 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.

bringing children up naturist

Sat Sep 24 1:18 AM by filmmakingally in Pregnancy & Parenting

It's about teaching children to make love so that they do it themselves. Love has no age or genetic requirement. It's healthy for young siblings to make love, and it's unhealthy if they don't. Sexual repression of children fucks them up as adults. Because the parents are secretive about it, children get the idea that it's bad, which starts the process of sexual repression.

Gross. Yuck. Eww. I've run out of ways to express how disgusted I am with what you've said here. Ewwwwwww!!!!!!!

No, siblings should not make love. It is in our genetic interest that we don't do this. Ever. This is a cultural universal.


learning to use a toilet

Sun Sep 11 2:33 PM by Angelica in Pregnancy & Parenting

My statement was meant to indicate that I'm not finished with my thoughts on this topic, rather than to create drama.

I believe parents in this world universally make a big mistake when it comes time to start thinking about their children using the toilet. Kids feel forced to do it, and this breeds resentment and damages their self-esteem. Having the father (the mother is needed in the battle against the patriarchy) stay home with the children and homeschool them while they haven't yet decided to train themselves is the way to avoid humiliation by their more-repressed peers.

I would also like to point out that limiting elimination to the toilet at any age creates situations where the person's health is compromised due to the lack of availability of a bathroom. In these situations, I strongly advise parents to let their children wear diapers no matter their age. Retention can lead to kidney stones, intestinal damage, urinary tract infections and harmful bacteria and toxins in the bloodstream.


How to Announce Baby #4?

Thu Sep 8 5:00 AM by Carol Palmer in Pregnancy & Parenting

FB pic is the best idea. All your friends and relatives can definitely post in comments or expressions . Consider yourself lucky to have many children. They are a blessing from God


How NOT to help parents with a newborn

Fri Jul 22 6:11 PM by missmay in Pregnancy & Parenting

oh, lord, i am so tired of people telling me to "enjoy it!" regarding my newborn. and asking me if she is a "good baby." how could a baby be bad? and how does it make me enjoy her more to be reminded to do so? i imagine that if i was depressed and had a colicky baby these questions would be even more obnoxious.


Kids are full of LIES

Sun May 22 2:29 PM by rowan in Pregnancy & Parenting

Don't be silly monk, everyone knows a good conglomerate goes better with milk


Don't give your kids antidepressants.

Thu Sep 15 9:13 PM by Nachos in Pregnancy & Parenting

Mental health issues will never start to hurt, therefore no preemptive treatment is needed.

Mental health issues hurt, take it from me. There are many psychosomatic disorders out there which affect your body even though the real problem is in your mind. But to get better, you HAVE to treat both. Pre-emptive treatment also can stop some disorders from becoming too bad. And yes, sometimes drugs can be very very helpful.

I don't think you know what you're talking about and all this "I know because of divine intuition" bullshit is starting to piss me off. if you ask others for sources, be kind enough to provide some yourself.

If this thread continues to be shit-slinging, I will lock it.


Middle grade / Beginning Chapter Books

Fri Sep 9 8:01 PM by melsbells in Pregnancy & Parenting

I think a big driver in getting them to read is to find stories that they like.
Definitely this. I once tutored a kid who had been held back twice in elementary school and was still a couple grade levels behind on reading skills. He was given a book from the Captain Underpants series because it was supposed to be at his reading level but he thought it was utterly stupid. I don't think we ever found books that both matched his reading level and maturity level, but once we started reading books better suited to his interests, it didn't matter that they were more difficult.

One of my cousins kids read the Warriors series and was really into it. She was bulllied in school, but I don't think it was instigated by her reading choices.

I don't know any recent books for this age group but I've heard great things about the Adventure Time comics.


Carriers vs Ring Sling

Mon Sep 5 8:59 PM by melsbells in Pregnancy & Parenting

^That's funny because the bjorn carrier is the one I was given that I didn't like. I think that just re-emphasizes that the same thing isn't going to work the same for everyone.


Denial Trends?

Thu Jul 21 7:24 PM by SameMom in Pregnancy & Parenting

Sorry, if I was not able to mention other details. Actually, I have a (US) medicare insurance. And I am particularly referring to this denial management software which help clients with their claims. Thanks for your reply. :)


minimalist kids birthday parties

Sun May 15 9:19 PM by melsbells in Pregnancy & Parenting

For the first two birthdays, we tried to make some special food and splurge on interesting fruit. If I lived closer to friends, I would want to throw a get-together as an excuse to see my friends, celebrate our survival of another year. I don't think my kid would actually be into that though. They are turning out to be quite introverted and shy.


Sleep Training for Parents and Infants

Wed Sep 14 4:04 AM by monk in Pregnancy & Parenting

This video is by my favorite health info series. There's always links to sources and the host is doctor very respected who writes medical articles for the NYTimes.
Get some sleep mom & dad.

jyPYf9jIuRE


Cry it out vs. Attachment

Mon Sep 5 5:20 PM by rowan in Pregnancy & Parenting

^Hm that reminds me of a thing I read about pushing reading (and by extension other things) in this country too. I'll see if I can't dredge it up.


Public Service Announcement: Furniture Anchors!

Fri Jul 1 5:17 AM by cwbyrvr in Pregnancy & Parenting

I do find it very interesting to find that IKEA is recalling furniture because people don't secure it to walls... I was given anchors with all of the stuff I've bought from there. Though maybe that's only a somewhat recent thing? It was over a half a year ago that I bought stuff from there, though.

And I didn't use the anchors... I guess I am about to be an aunt and it might be a good idea to get that stuff secured in case I ever end up watching my niece here. Hadn't really worried about it prior because there was literally never going to be a time I'd have kids running around this place. The likelihood of my niece ever being here is pretty damn low too, but I wouldn't say 0%.


Pregnancy Guidebooks for Cool Moms (humor)

Wed May 11 3:39 PM by rowan in Pregnancy & Parenting

One of my friends is part of this magazine. She didn't write this one but it's pretty hilarious.

http://theoffingmag.com/wits-end/pregna ... cool-moms/

Anyone want to come up with our own "Guidebook" titles?

spoiler:
the one about inducing labor by setting your hair on fire is my favorite