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 (

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.

the worst first birthday invite ever

Mon Apr 27 7:36 PM by jen4knits in Pregnancy & Parenting

Wow. I kinda get the trying to request gifts that you know you'll use with your kid, but I think these parents missed the point that gifts are just that, gifts. No one is required to buy your kid anything and telling people full out "we don't keep anything you give us and return it all" is rude in my mind. My mom always taught me to smile and say thank you, regardless of the gift as the person giving it to you thought you'd appreciate it. (Granted I know some people are terrible shoppers for others-still). I don't understand why if you are trying to keep things to a "2 gift max" per family unit, but then wouldn't it be the gift givers choice on what those 2 things are? Then they can feel it's not just a transfer of goods and they can feel like the gift actually matters.

The responsibility of choosing a name

Wed Apr 8 11:32 PM by C˙glas in Pregnancy & Parenting

Spouse and I have two main rules: family name and not Biblical. Fortunately we have big families with lots of cool names available.

I have the additional stipulations of not having two people in the same house with the same name (i.e. Jr.) and that really unusual names should be middle names. Spouse's family has the tradition of naming the first son after the father, but since Spouse has a super-Biblical name I've not had to fight too hard to keep him from naming his son after himself. I was named after my dad's mom so we had the same first and last name in the same town and that caused some problems (which, admittedly, were quickly solved by our 70-year difference in ages). But I can't imagine having two "Spouse"s at one address.

Spouse's family has quite a few Anglicized Polish names, and Spouse wants to revive the pre-immigration names, which I'm fine with but would prefer them as middle names: Cunegunda and Waslav are a lifetime of "What? How do you spell that? Where is that from? Did your parents make that up?" If the kid really wants to use it, which would be cool, they can always choose to use their middle name.

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.

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.

name trends

Wed Jan 28 8:58 AM by Lemon in Pregnancy & Parenting

Some of my family members who work in the healthcare system have overheard some doozies.

I work in healthcare, so I can relate. I think my favourite was a kid called "Abcde" which we were assured was pronounced "Abasidee". Mirena was a cute choice, named after the contraceptive device. Then there have been some good narrative names including places of birth - e.g. "Shell" (after the baby born in a petrol station carpark) - and places of conception - e.g. "...(a suburb which I'll keep secret - just in case this somehow breaches some poor kid's privacy) bus stop."

Can't find my tribe

Mon Apr 27 7:25 PM by jen4knits in Pregnancy & Parenting

We are expecting our first and I have definitely started noticing the "boys will be boys" and "girls like pink" crap that is out there. I said to my husband the other day how sad it is I'm glad our first child is a boy because it will be easier to promote our science/math/computer mindset without too much headache with family. Granted if this little one happens to turn out to be a girl then well she'll get the same up bringing we're planing for "Junior". Or if "Junior" wants to be a ballerina we'll be perfectly fine with that. I am fortunate that my mom and the important people of my side of the family don't give two flying flips if he has a doll or learns tap dancing or whatever. My hubby's family might be a little harder to get to accept things, but with the latest drama we won't have to deal with most of them once kiddo comes to being.

I do agree the best thing to do is try and speak up when needed, but of course that's easier said than done. Good luck as I have yet to find any close friends that I can relate to with this type of thing, which I also find sad.

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).


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.

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:

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

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.???

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.

It takes 13 million calories to raise a child!

Sun Mar 15 6:33 PM by Metcodon1 in Pregnancy & Parenting

Child care is BEYOND insanely expensive... When my husband and I were deciding to to have children we agreed to both go part time (4 days a week) in order to make our lives easier (we both make more than we would pay for day care, so we did take a financial hit with this decision). For example, whoever is home on a given day can throw in some laundry, or some food into the slow cooker, run errands... All of these things multiply in number once you have kids at the same time becoming more difficult to schedule. Unfortunately, when my daughter was around 1 my work situation changed and I had to go full time... let me tell you, it was definitely easier when I wasn't.

Anyway, the point I am getting to here is, when kids are little they require a lot of attention and sometimes (often?) some career sacrifice but it's TEMPORARY. When we decided to get pregnant we agreed that we would both slow down career wise for 5 years. For us it means, we do our jobs, we come home. We don't sign up for extra projects, we try to limit our travel, but it's all just for now. We also decided to have our kids close together for that reason (they'll be 2 years apart). Anyway, it's something to keep in mind. An 8 year old goes to school and doesn't need constant monitoring to keep from killing him/herself. It's ok to decide to slow down for a period of time, knowing that you'll come roaring back once they're older.

Because judging other parents is absurd.

Tue Feb 3 7:05 AM by Zeph in Pregnancy & Parenting

It's alright to discuss these topics, but there needs to be boundaries. I would use the following, personally:

1. Don't insert yourself into a stranger's situation or bring up the topic yourself to a stranger.
2. It's probably not your business if you're not a parent yourself.
3. Ask the person why they are making these choices, don't assume.
4. Try to end on a positive note.

I don't feel right bringing up to my sister that I don't agree that she spanks my nephew, but after being a teacher, I am pretty forgiving of parents' choices. It's the hardest role there is. Even though I want to raise my children on nutritious meals, cloth diapers, and museum passes, I know I'm going to slip up and give them fries, Huggies, and Disney DVD's.

I also feel that home birth is a fine option for low-risk births, where the mother is well coached and the midwife is reputable. If you live near a hospital and your midwife is highly qualified, why not? They have equipment. I won't be choosing this option, but with any birth plan there needs to be a series of precautions taken.

sleep humor

Fri Jan 23 7:13 PM by rowan in Pregnancy & Parenting

Here's a really funny humor bit about sleep, but the same general idea can apply to pretty much any "advice" given to new parents.

"I bought all the top books on baby sleep and development. I read through them all, as well as several blogs and sleep websites. I gathered lots of advice:" ... babybooks/