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 August 28th, 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 July 24th, 2015 35W, 0D 0.01% 0.02% -% -% -% 0.1% 0.1% 0.2%
Saturday July 25th, 2015 35W, 1D 0.01% 0.03% -% -% -% 0.1% 0.2% 0.3%
Sunday July 26th, 2015 35W, 2D 0.02% 0.05% -% -% -% 0.1% 0.2% 0.4%
Monday July 27th, 2015 35W, 3D 0.02% 0.07% -% -% -% 0.1% 0.3% 0.6%
Tuesday July 28th, 2015 35W, 4D 0.03% 0.1% -% -% -% 0.2% 0.4% 0.7%
Wednesday July 29th, 2015 35W, 5D 0.04% 0.13% -% -% -% 0.2% 0.5% 0.9%
Thursday July 30th, 2015 35W, 6D 0.06% 0.19% -% -% 0.1% 0.3% 0.6% 1.2%
Friday July 31st, 2015 36W, 0D 0.08% 0.26% -% -% 0.1% 0.4% 0.8% 1.5%
Saturday August 1st, 2015 36W, 1D 0.1% 0.35% -% -% 0.1% 0.5% 1% 1.9%
Sunday August 2nd, 2015 36W, 2D 0.14% 0.47% -% -% 0.1% 0.6% 1.3% 2.4%
Monday August 3rd, 2015 36W, 3D 0.18% 0.62% -% -% 0.2% 0.8% 1.7% 3%
Tuesday August 4th, 2015 36W, 4D 0.22% 0.82% -% -% 0.2% 1% 2.1% 3.7%
Wednesday August 5th, 2015 36W, 5D 0.28% 1.07% -% -% 0.3% 1.2% 2.5% 4.5%
Thursday August 6th, 2015 36W, 6D 0.35% 1.39% -% -% 0.4% 1.5% 3.1% 5.4%
Friday August 7th, 2015 37W, 0D 0.44% 1.79% -% -% 0.4% 1.8% 3.8% 6.4%
Saturday August 8th, 2015 37W, 1D 0.54% 2.28% -% -% 0.6% 2.2% 4.5% 7.6%
Sunday August 9th, 2015 37W, 2D 0.66% 2.87% -% -% 0.7% 2.7% 5.4% 8.9%
Monday August 10th, 2015 37W, 3D 0.79% 3.59% -% -% 0.8% 3.2% 6.3% 10.4%
Tuesday August 11th, 2015 37W, 4D 0.94% 4.46% -% -% 1% 3.8% 7.4% 11.9%
Wednesday August 12th, 2015 37W, 5D 1.11% 5.48% -% -% 1.2% 4.4% 8.6% 13.7%
Thursday August 13th, 2015 37W, 6D 1.3% 6.68% -% -% 1.4% 5.2% 9.8% 15.5%
Friday August 14th, 2015 38W, 0D 1.5% 8.08% -% -% 1.6% 6% 11.2% 17.5%
Saturday August 15th, 2015 38W, 1D 1.71% 9.68% -% -% 1.9% 6.9% 12.7% 19.7%
Sunday August 16th, 2015 38W, 2D 1.94% 11.51% -% -% 2.2% 7.8% 14.3% 21.9%
Monday August 17th, 2015 38W, 3D 2.18% 13.57% -% -% 2.5% 8.8% 16% 24.2%
Tuesday August 18th, 2015 38W, 4D 2.42% 15.87% -% -% 2.9% 9.9% 17.8% 26.6%
Wednesday August 19th, 2015 38W, 5D 2.66% 18.41% -% -% 3.3% 11.1% 19.7% 29%
Thursday August 20th, 2015 38W, 6D 2.9% 21.19% -% -% 3.7% 12.3% 21.6% 31.5%
Friday August 21st, 2015 39W, 0D 3.12% 24.2% -% -% 4.1% 13.5% 23.6% 34%
Saturday August 22nd, 2015 39W, 1D 3.33% 27.43% -% -% 4.6% 14.9% 25.6% 36.6%
Sunday August 23rd, 2015 39W, 2D 3.52% 30.85% -% -% 5.1% 16.2% 27.7% 39.2%
Monday August 24th, 2015 39W, 3D 3.68% 34.46% -% -% 5.6% 17.6% 29.8% 41.7%
Tuesday August 25th, 2015 39W, 4D 3.81% 38.21% -% -% 6.2% 19.1% 31.9% 44.2%
Wednesday August 26th, 2015 39W, 5D 3.91% 42.07% -% -% 6.7% 20.6% 34% 46.7%
Thursday August 27th, 2015 39W, 6D 3.97% 46.02% -% -% 7.4% 22.1% 36.2% 49.2%
Friday August 28th, 2015 40W, 0D 3.99% 50% 8% 0% 8% 23.6% 38.3% 51.6%
Saturday August 29th, 2015 40W, 1D 3.97% 53.98% 7.9% 8% 8.6% 25.1% 40.4% 54%
Sunday August 30th, 2015 40W, 2D 3.91% 57.93% 7.8% 15.9% 9.3% 26.7% 42.5% 56.2%
Monday August 31st, 2015 40W, 3D 3.81% 61.79% 7.6% 23.6% 10% 28.2% 44.5% 58.5%
Tuesday September 1st, 2015 40W, 4D 3.68% 65.54% 7.4% 31.1% 10.7% 29.8% 46.6% 60.6%
Wednesday September 2nd, 2015 40W, 5D 3.52% 69.15% 7% 38.3% 11.4% 31.3% 48.6% 62.7%
Thursday September 3rd, 2015 40W, 6D 3.33% 72.57% 6.7% 45.1% 12.1% 32.9% 50.5% 64.7%
Friday September 4th, 2015 41W, 0D 3.12% 75.8% 6.2% 51.6% 12.9% 34.4% 52.4% 66.6%
Saturday September 5th, 2015 41W, 1D 2.9% 78.81% 5.8% 57.6% 13.7% 36% 54.3% 68.5%
Sunday September 6th, 2015 41W, 2D 2.66% 81.59% 5.3% 63.2% 14.4% 37.5% 56.1% 70.2%
Monday September 7th, 2015 41W, 3D 2.42% 84.13% 4.8% 68.3% 15.2% 39% 57.9% 71.9%
Tuesday September 8th, 2015 41W, 4D 2.18% 86.43% 4.4% 72.9% 16.1% 40.5% 59.6% 73.5%
Wednesday September 9th, 2015 41W, 5D 1.94% 88.49% 3.9% 77% 16.9% 42% 61.3% 75.1%
Thursday September 10th, 2015 41W, 6D 1.71% 90.32% 3.4% 80.6% 17.7% 43.4% 62.9% 76.4%
Friday September 11th, 2015 42W, 0D 1.5% 91.92% 3% 83.8% 18.6% 44.8% 64.5% 77.8%
Saturday September 12th, 2015 42W, 1D 1.3% 93.32% 2.6% 86.6% 19.5% 46.3% 65.9% 79.2%
Sunday September 13th, 2015 42W, 2D 1.11% 94.52% 2.2% 89% 20.3% 47.6% 67.3% 80.5%
Monday September 14th, 2015 42W, 3D 0.94% 95.54% 1.9% 91.1% 21.1% 48.9% 68.8% 81.6%
Tuesday September 15th, 2015 42W, 4D 0.79% 96.41% 1.6% 92.8% 22% 50.1% 70.2% 82.7%
Wednesday September 16th, 2015 42W, 5D 0.66% 97.13% 1.3% 94.3% 23% 51.6% 71.4% 83.6%
Thursday September 17th, 2015 42W, 6D 0.54% 97.72% 1.1% 95.4% 23.7% 53.1% 72.8% 84.6%
Friday September 18th, 2015 43W, 0D 0.44% 98.21% 0.9% 96.4% 24.6% 54.2% 73.7% 85.5%
Saturday September 19th, 2015 43W, 1D 0.35% 98.61% 0.7% 97.2% 25.2% 55.4% 74.8% 86.3%
Sunday September 20th, 2015 43W, 2D 0.28% 98.93% 0.6% 97.9% 26.2% 56.1% 75.7% 87.9%
Monday September 21st, 2015 43W, 3D 0.22% 99.18% 0.4% 98.4% 26.8% 57.3% 76.8% -%
Tuesday September 22nd, 2015 43W, 4D 0.18% 99.38% 0.4% 98.8% 29% 58.1% 79% -%
Wednesday September 23rd, 2015 43W, 5D 0.14% 99.53% 0.3% 99.1% 29.8% 59.6% -% -%
Thursday September 24th, 2015 43W, 6D 0.1% 99.65% 0.2% 99.3% 28.6% 62.9% -% -%
Friday September 25th, 2015 44W, 0D 0.08% 99.74% 0.2% 99.5% 30.8% -% -% -%
Saturday September 26th, 2015 44W, 1D 0.06% 99.81% 0.1% 99.6% 31.6% -% -% -%
Sunday September 27th, 2015 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.

Body Betrayal

Thu Aug 27 8:44 PM by mathnome in Pregnancy & Parenting

Ugh.

I'm currently 37 weeks, and while almost all my immediate coworkers have been super supportive of my being at work (and planning to continue being at work), I got a "tsk tsk" from another woman the other day about not taking my leave yet, and she hasn't been the first one. (Interestingly, so far it's only been the women who seem to think I'm supposed to leave already.)

Anyway, my line has been, "I'm really enjoying my project right now. I might as well enjoy it while I can!" (Which is true, and also generally shuts them up.)

Good luck! I hope the BP stays under the magic threshold.


What did you hate hearing when you were pregnant?

Mon Aug 24 11:52 AM by DarkOne in Pregnancy & Parenting


3. I think you're putting on too much weight. You know it''s going to make it harder to get your body back. (I'm 6 months post baby today, so now the comments have turned to "I told you!")


WHAAAAAT????
http://static1.wikia.nocookie.net/__cb20130207210531/disney/images/thumb/0/0b/Hercules-disneyscreencaps.com-1020.jpg/640px-Hercules-disneyscreencaps.com-1020.jpg


Braxton Hicks questions

Sat Aug 15 1:06 AM by quellybelly in Pregnancy & Parenting

I've had BH contractions since early 2nd trimester. Never been painful. More like somebody was vacuum sealing my entire stomach.


Kids books we hate

Mon Aug 3 1:10 PM by Sonic# in Pregnancy & Parenting

I absolutely loved at least one of the Berenstain Bears books (one based off of the Tortoise and the Hare), but I also hate at least one of them. The Berenstain Bears and the Trouble With Chores features a Mama Bear exasperated that no one is doing chores, with the kid bears and Papa Bear keep excusing themselves out of doing them. Rather than coming to some equitable distribution of labor by the end, the house gets really bad and the kids and pop finally binge clean. The situation didn't seem solved; Mama Bear just seemed pacified.


for all you moms and future moms

Tue Jul 21 2:28 AM by DarkOne in Pregnancy & Parenting

Eek and here I was about to say this felt like a tame version of Mother Lover.


Happy Birthday, Baby Bird!

Thu Aug 27 12:57 PM by ablotial in Pregnancy & Parenting

Cute kids, and I love the cupcake theme!


mom guilt bingo

Sun Aug 23 11:06 AM by ohbonobogirl in Pregnancy & Parenting

Adding to the newborn edition:
Knowingly fell asleep on the couch with baby on your chest because...sleep...
Used a tablet or phone to surf net or play games while nursing rather than cherishing every moment
Took baby out in public solely because it's really great to hear strangers compliment your adorable little being.


let's list our favorite children's books

Tue Aug 11 3:49 AM by DarkOne in Pregnancy & Parenting

As a grade school kid, I spent a lot of time perusing dictionaries, atlases and world almanacs. I blame it on my Big Bird's Sesame Street Dictionary, which was awesome:

https://img1.etsystatic.com/000/0/6267461/il_570xN.298036045.jpg
http://www.joemathieu.com/images/sesame_street_dictionary_open_book.jpg

Did anyone else own these? I have the full set stashed somewhere for when my kid is old enough.


RIE parenting

Sat Aug 1 2:09 AM by ohbonobogirl in Pregnancy & Parenting

I encountered this randomly the other day. Now I need to go dig some more into it...


the wonder weeks: practical help for parents or self-fulfilling quackery?

Mon Jul 20 2:29 AM by geerlady in Pregnancy & Parenting

I am actually a big fan of the wonder weeks. I found it better than most popular level books looking at infant development. My son was right on the clock for the fussy/happy times, and it was interesting to look for the new skills that I might not have noticed if I hadn't been watching for them.

On the other hand, I stumbled upon this accidentally, so didn't have any hype surrounding it. I also read the author biographies before picking up the book, so took everything with a grain of salt knowing that 1) the authors specialized in chimpanzees, not humans, and developed their theories based on chimps; 2) the bulk of the research is greater than 20 years old and so much of the book is out-dated; and 3) given #'s 1&2, incidental parenting advice had to be filtered.

That said, I still found the book useful and regularly recommend it to people.


What new thing did your baby do this week?

Mon Aug 24 5:56 PM by Nachos in Pregnancy & Parenting

It's not my baby, but my sister taught my best friend's baby how to fist bump and I taught her how to say yolo. Heh.


What the Hell just entered my earhole?

Mon Aug 17 11:34 AM by DarkOne in Pregnancy & Parenting

Oh that reminded me of a friend's kid... My friend, her 6-yr old son and her 9-yr old daughter were driving to school in the morning, when the son proudly declared "When I grow up I want to be a racist." My friend said she went O_O and her daughter went on a rant as to how horrible of an idea that was... The son was all sad and confused when he responded "But I really love race cars!"

That cracked me up.


teething necklaces

Tue Aug 4 7:12 PM by DarkOne in Pregnancy & Parenting

They'll chew on anything and everything. And I think you may have the scale wrong. These are large silicone beads. Think of it as a teething/chewing toy that is long enough to be worn around mom's neck. This isn't a string of pearls that will break if you tug on it and you'll and up with a mess of pearls on the floor or in baby's mouth. Google images for "babies and chew beads".
http://homemademothering.com/wp-content/uploads/2013/04/DSC7453.jpg
http://www.frugalcouponliving.com/wp-content/uploads/2012/05/chew-beads.jpg
And these are not at all related to those dumb amber necklaces...


do you have a parenting goal?

Sun Jul 26 5:16 PM by rosefox in Pregnancy & Parenting

I'm definitely in the "happy healthy child is my only goal" camp. I know some people who are superstars in their chosen fields. From what I can tell, being a superstar is completely exhausting and often really psychologically taxing. So if my kid isn't naturally inclined that way, I certainly don't intend to push them.

If I'm hoping for anything, I hope they'll end up being a quirky artsy/techy type like just about everyone else in the family. But my brother's a corporate lawyer and I love him anyway, so even if our kid turns out to be a white sheep, they'll just bond with Uncle A and it'll all be fine. :)


Spacefem's homemade playdoh recipe

Mon Jul 13 3:01 AM by Zeph in Pregnancy & Parenting

A parent in my Kindergarten class would bring us homemade purple play dough that smelled like grape!