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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.

if you need to breastfeed, please cover yourself

Fri May 29 3:43 PM by rowan in Pregnancy & Parenting

word to the wise though about summer babies - boob sunburn!!
Ok, THAT is a valid reason to cover up. Ouch!!!


getting along while doing things differently

Wed May 20 9:11 AM by Gnarlbanya in Pregnancy & Parenting

I'm finding it interesting that some people I've encountered (online) presume that if they know one of your pregnancy or parenting preferences or opinions, they can extrapolate them all. For example, in discussing pain relief options recently, after expressing my desire not to have an epidural it was also assumed that I would forego vaccinations for my child and would be automatically pro home VBAC. When I made it clear that this wasn't the case, people were more annoyed than they would have been had I just said I wanted an epidural. There seems to be a really odd sort of tribalism around many of these choices, and a strange playground mentality whereby you can't deviate from the 'norm' (made harder to navigate because different groups have very different norms). For me, my preference to go without an epidural is not out of any desire to have a more natural experience but more because I want to be able to walk around and I find the idea of having a catheter just horrible. That doesn't mean that I judge anyone else's choices or motives that differ from mine, though. I do think it's worth remembering that people may make identical choices for very different reasons.


the worst first birthday invite ever

Wed Apr 29 7:52 PM by melsbells in Pregnancy & Parenting

the understanding that when people buy gifts, it's their way of saying "hey, this says something about me, I want your kid to have it because we have a relationship." two ways.

Except sometimes those gifts are inappropriate. Part of me feels a lot of sympathy for these parents because what can I do with gifted clothing that is already too small for my kid except pass them on? What can I do with gifts that conflict with my personal beliefs, like a racist book that I don't want to inflict on anyone else either?


Tips and pitfalls for gender-neutral parenting

Mon Mar 30 9:25 PM by rowan in Pregnancy & Parenting

^I agree with that! :)

Part of "gender neutral" parenting is supplying the side of things that doesn't get given by other people.


How did you decide how many kids to have?

Fri Feb 27 2:42 AM by MFS in Pregnancy & Parenting

First 2 were on purpose, 3rd kinda not so much, 4th was totally an oops (when you think things are broken, they have this habit of fixing themselves). Made sure we were done after that. Aside from that, we knew we'd have at least 2, likely 3, but the timing was not at all what we thought we were "planning". Such is life.


cosleeping

Fri May 29 3:42 AM by ablotial in Pregnancy & Parenting

I'm fully prepared for all plans to go out the window - the ultimate goal will be sleeping (for everyone) so if we have to add the 'co', so be it.



Seconding this!


Can't find my tribe

Sat May 9 9:25 PM by Nedra in Pregnancy & Parenting

We've found relatively like-minded parents in the following ways:

-We went to undergrad at a liberal arts college and most of our alumni friends live in town still.
-I worked for 5 years at a charter school that was "girl-focused" (meaning, it was a girls school and any student who identified as a girl -- either biologically or socially -- could attend as long as they were cool with being part of a community of girls). Deconstructing sexism, heterosexism and racism was part of our mission and so the staff was very like-minded in this regard.

That's where virtually all my local, like-minded parents came from. Our church is pretty open-minded too. I don't know that I've ever seen a boy in a dress there, but I can't really imagine anyone batting an eye if we did. Certainly lots of boys playing with dolls and girls with trucks in the nursery.

When my own parents were in this position, they started a "non-sexist parenting group." Basically, they found ONE family who felt the same way, that family knew another, etc. They built a community intentionally by voicing out loud that that was what they wanted and spreading the word. They also found a lot of like-minded people through church. We are hippy-church and hippy-daycare/school people, so that helps.


Bilingual Babies

Mon Apr 13 11:41 AM by sakooon in Pregnancy & Parenting

Spacefem's husband no longer speaking Spanish and Nachos no longer speaking Dutch, I think are great examples of lacking motivation. Likewise, I had mentioned that my kid is unlikely to pick up Swedish, despite 10% of the population being native Swedish speakers, Swedish being one of the offical languages and therefore alongside Finnish everywhere, and having a Swedish speaking uncle.???


Interacting with parents whose choices you don't trust

Thu Mar 26 3:08 PM by rowan in Pregnancy & Parenting

How can you tell who has been vaccinated or not?
That's the tricky part, you can't really. So unless the parents say something you never actually know.


Bonding

Fri Feb 6 4:35 AM by Zeph in Pregnancy & Parenting

Bonding with my future infant is a concern of mine, because my depression is debilitating. I'm relieved to know that normally functioning women don't feel that head-over-heels mushy baby love.


Flying during third trimester

Wed May 27 2:03 AM by ablotial in Pregnancy & Parenting

Thanks, I love the part about not being able to lower the tray table all the way :) I never would have thought of that.

Normally, my doctor said not to do aspirin or ibuprofen for pain relief, but only tylenol (acetemenophen) and even that only if -absolutely- needed after trying other remedies (like heat pack, cold pack, resting with lights closed eyes shut, etc). But the directions for flying specifically say to take one baby aspirin (81mg) a day for three days before the flight as well as the day of the flight to prevent blood clots. My guess is the risk of such a small dose is outweighed by the benefit of not getting blood clots for this particular situation.


The responsibility of choosing a name

Wed Apr 29 8:02 PM by melsbells in Pregnancy & Parenting

I fretted way too much about this.

Finland is one of the countries in the world with an approved name list. People can deviate from the list, but then they need to participate in bureacracy. Foreigners often get approval for names from their home culture, but as someone from the U.S., I'm not sure how straightforward it is to say "this cultural name appropriately represents my culture". Do I pick the cultures of my ancestors or modern U.S. conglomeration?

We went with approved names, but not the Swedish ones because my spouse felt weird giving a Swedish name without Swedish heritage. The Swedish names would have been most easily recognizable for my family.

Our main criteria ended up including:
Finnish
I could pronounce it
we didn't hate the way Americans would pronounce it

We had to eliminate one contender because I sometimes mispronounced it, turning the name into a word that meant "failure".


Advice for non-parents?

Tue Apr 7 8:56 PM by Nedra in Pregnancy & Parenting

I definitely agree on the flexibility of where to meet. It makes a huge difference when you aren't stressed about your kid in a public place. Recently, I went to a tea shop with my daughter. Not only was the layout of the seating area very conducive to letting a toddler walk around a bit while still keeping a close eye on her, but there was plenty of room for my stroller and plenty of available tables. That is rare! It wasn't a huge space, but it was just laid out well for what we needed. I will definitely be suggesting it the next time a friend asks if we can get together. Let your parent friends choose the location! They know which places have changing tables and room to park a stroller.


How Good Parents Miss Child Sexual Abuse and 5 Questions to Change That

Tue Mar 24 3:20 AM by rowan in Pregnancy & Parenting

And that includes parents too - I try to always ask "can I have a hug/kiss" rather than "give me a hug/kiss" and that she can always always say no if she doesn't want to, even with me. (She's old enough now that I've had enough practice that even writing "give me a hug" sounds weird to me)

Also I think on a more general level it's good to practice asking these kinds of questions anyway. Not just for abuse, but in general if you want to know what's going on in their life. Asking "how was school" gets an "I dunno" even now, but asking more specific things like "What was something funny that happened today" or "What did you do at recess?" really gets her talking more. Not sure where I read that, but the kinds of questions above made me think that sometimes just asking a better question will help get at what you want to know more than asking generalities.

The other thing is definitely definitely not making judgment on those things that they're saying. Instead try "What did you think about that ?" or "What did you do when happened?" "What would make you feel safe?" "What could you try if that happens again?" "Is there anything you'd like me to do?" These are things that I've asked wrt other kids on the playground (pushing etc) but I think it's the same idea in terms of empowering the child to talk about things that happen and letting them help come to the conclusions. Which isn't to say you can't help them get there by suggesting actions they could do, etc, just that if you get them talking about things that happen on a daily basis then if something weird happens then they'll likely be more comfortable telling you, especially if you've already shown them what boundaries there are and respecting those boundaries (like not tickling if they say they don't want to be tickled etc).


34 Weeks

Fri Jan 23 11:57 PM by Sonic# in Pregnancy & Parenting

Probably not. As we pointed out in the other topic, 34 weeks isn't even on the chart because it's so rare:
http://spacefem.com/pregnant/charts/duedate1.php

You'd be better off worrying over a car accident.