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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. Waldenstr├Â) 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.

let's list our favorite children's books

Sat Aug 1 2:53 PM by spacefem in Pregnancy & Parenting

Our favorite read alouds right now:

berenstain bears spooky old tree
More bears!
A Pet For Petunia (adorable book about a little girl who loves skunks)
Down on the Farm - good rhythm book for the toddler
Pete the cat and his groovy buttons
pigeon wants a puppy

And anything by sandra boynton but the best is "not the hippopotamus"

My favorite little baby book was "global babies" - both my babies loved pictures of faces and babies so now it's my go to gift book. I also love the "that's not my..." series with textures. "That's not my pirate" has a girl pirate and that's pretty kick ass :)

I'll be adding more I'm sure, we read a ton and I have to keep changing a lot to keep myself sane lol


Newborns are difficult!

Sat Aug 1 2:03 AM by ohbonobogirl in Pregnancy & Parenting

Yay for better, if not yet great. The pacifier has been wonderful for my little creature. I was hesitant to use it, just like you, but it calms him like nothing else and he still eats like a champ. Best wishes!


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. :)


Diaper bags

Wed Jul 15 3:46 AM by geerlady in Pregnancy & Parenting

We used/still use our diaper bag quite a lot.

For our little guy's first year of life we were urban dwellers and I would often go out for half a day at a time. I would take a diaper for every hour I planned to be out of the house plus one, which was too much for the clutch. I needed a change pad, since he was often changed in nasty places, wipes, hand sanitizer (for changes away from running water), Kleenex, and disposal bags. He needed spare clothes, I needed a spare shirt (discovered after an emergency, useful many times afterwards), and it was useful to have a plastic bag for clothes which were victims of a diaper explosion. For longer days out I would bring two spares for him (and did have days where I used both). I would also have a nursing cover and a blanket in there. We also had a stroller cover for napping which was quite handy when we were taking the stroller as opposed to a carrier. And then there was my stuff, like my wallet, phone, lip balm, keys, granola bar, etc... I did pack the camera, and was often glad for it. Nearly all of our first year pics were from our little excursions.


Pregnancy insomnia

Thu Jun 25 9:05 AM by Gnarlbanya in Pregnancy & Parenting

Thanks for the tips. It's not so much getting to sleep that's the problem, it's staying that way that is causing the issue - too many things waking me up. I seem to be in a bit of a pattern now of alternating good and bad nights, which I guess I can live with. Meanwhile, Netflix is getting a damn good workout in the early hours.


What new thing did your baby do this week?

Sat Aug 1 3:16 AM by Isabella357 in Pregnancy & Parenting

4 year old: I overheard her Barbie tell Ken that he had a "serious revenue recognition problem" and that they needed to go to the doctor for it. (Little ears that listen when Mommy works from home combined with the doctor obsession)

3 year old: Caught me watching a sad movie and gave me a hug, kiss, and pat on the back with an "It's okay, Mommy." This is significant to me because I was starting to worry about how little this kid cares about anything, let alone others. It only took 3 years for this little boy to show empathy and respond appropriately.

5 month old: Ate about a spoonful of baby cereal? So he still only eats and poops. He's still my favorite since he can't talk back or run away. hahaha


teething necklaces

Thu Jul 30 11:41 AM by DarkOne in Pregnancy & Parenting

A few of the more enterprising/crafty moms in my old parent group got together with a group of friends and bought beads in bulk from alibaba or some other site like that. Some sold the necklaces locally, some made really affordable gifts for friends; I almost jumped in, because a couple of years ago these were still hovering at the $30 mark, but at ~$15, they're much more affordable now, methinks.

They babies I witnessed munching on these were really going to town on them, too.


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.


if you need to breastfeed, please cover yourself

Mon Jul 13 12:32 PM by DarkOne in Pregnancy & Parenting

Sorry to CPR a dying thread, but I came across this, and thought I'd share.

LURZqBig734


Antidepressants during pregnancy

Thu Jun 25 1:03 AM by Aum in Pregnancy & Parenting

http://www.henriettes-herb.com/blog/pos ... ssion.html

Pre and post-partum depression have similar reasons, physically speaking. Check nutrition first.


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...


Braxton Hicks questions

Mon Jul 27 2:13 PM by Metcodon1 in Pregnancy & Parenting

In my experience "real" contractions are pretty much the whole uterus (top, bottom and lower back). I remember reading somewhere that the ones that get you dilated from 0-7/8 cm are largely the muscles pulling up, trying to stretch the cervix out. As a result many people largely do feel them most strongly at the top of their belly. Whether you feel them strongly in your back or not depends on how the baby is positioned. If you've heard the term "back labor" that usually happens if the back of the baby's head is pressed up against your spine (less common than when the baby's face is on the spine). The contractions that take you from 7 or 8 cm to 10 - i.e. the ones in the part of labor known as "transition" - do tend to be lower down (and also more painful). That said, I think there is A LOT of variation in experience...


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.


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!


cosleeping

Fri Jun 12 4:01 PM by spacefem in Pregnancy & Parenting

Thanks! I was going to put my labor story in Random but never got around to it. I can try to do it soon - it's written out already so just a matter of editing.

Yes you must! I'm happy to hear from you, hope everything went and is going well :)