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 December 20th, 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
Sunday November 15th, 2015 35W, 0D 0.01% 0.02% -% -% -% 0.1% 0.1% 0.2%
Monday November 16th, 2015 35W, 1D 0.01% 0.03% -% -% -% 0.1% 0.2% 0.3%
Tuesday November 17th, 2015 35W, 2D 0.02% 0.05% -% -% -% 0.1% 0.2% 0.4%
Wednesday November 18th, 2015 35W, 3D 0.02% 0.07% -% -% -% 0.1% 0.3% 0.6%
Thursday November 19th, 2015 35W, 4D 0.03% 0.1% -% -% -% 0.2% 0.4% 0.7%
Friday November 20th, 2015 35W, 5D 0.04% 0.13% -% -% -% 0.2% 0.5% 0.9%
Saturday November 21st, 2015 35W, 6D 0.06% 0.19% -% -% 0.1% 0.3% 0.6% 1.2%
Sunday November 22nd, 2015 36W, 0D 0.08% 0.26% -% -% 0.1% 0.4% 0.8% 1.5%
Monday November 23rd, 2015 36W, 1D 0.1% 0.35% -% -% 0.1% 0.5% 1% 1.9%
Tuesday November 24th, 2015 36W, 2D 0.14% 0.47% -% -% 0.1% 0.6% 1.3% 2.4%
Wednesday November 25th, 2015 36W, 3D 0.18% 0.62% -% -% 0.2% 0.8% 1.7% 3%
Thursday November 26th, 2015 36W, 4D 0.22% 0.82% -% -% 0.2% 1% 2.1% 3.7%
Friday November 27th, 2015 36W, 5D 0.28% 1.07% -% -% 0.3% 1.2% 2.5% 4.5%
Saturday November 28th, 2015 36W, 6D 0.35% 1.39% -% -% 0.4% 1.5% 3.1% 5.4%
Sunday November 29th, 2015 37W, 0D 0.44% 1.79% -% -% 0.4% 1.8% 3.8% 6.4%
Monday November 30th, 2015 37W, 1D 0.54% 2.28% -% -% 0.6% 2.2% 4.5% 7.6%
Tuesday December 1st, 2015 37W, 2D 0.66% 2.87% -% -% 0.7% 2.7% 5.4% 8.9%
Wednesday December 2nd, 2015 37W, 3D 0.79% 3.59% -% -% 0.8% 3.2% 6.3% 10.4%
Thursday December 3rd, 2015 37W, 4D 0.94% 4.46% -% -% 1% 3.8% 7.4% 11.9%
Friday December 4th, 2015 37W, 5D 1.11% 5.48% -% -% 1.2% 4.4% 8.6% 13.7%
Saturday December 5th, 2015 37W, 6D 1.3% 6.68% -% -% 1.4% 5.2% 9.8% 15.5%
Sunday December 6th, 2015 38W, 0D 1.5% 8.08% -% -% 1.6% 6% 11.2% 17.5%
Monday December 7th, 2015 38W, 1D 1.71% 9.68% -% -% 1.9% 6.9% 12.7% 19.7%
Tuesday December 8th, 2015 38W, 2D 1.94% 11.51% -% -% 2.2% 7.8% 14.3% 21.9%
Wednesday December 9th, 2015 38W, 3D 2.18% 13.57% -% -% 2.5% 8.8% 16% 24.2%
Thursday December 10th, 2015 38W, 4D 2.42% 15.87% -% -% 2.9% 9.9% 17.8% 26.6%
Friday December 11th, 2015 38W, 5D 2.66% 18.41% -% -% 3.3% 11.1% 19.7% 29%
Saturday December 12th, 2015 38W, 6D 2.9% 21.19% -% -% 3.7% 12.3% 21.6% 31.5%
Sunday December 13th, 2015 39W, 0D 3.12% 24.2% -% -% 4.1% 13.5% 23.6% 34%
Monday December 14th, 2015 39W, 1D 3.33% 27.43% -% -% 4.6% 14.9% 25.6% 36.6%
Tuesday December 15th, 2015 39W, 2D 3.52% 30.85% -% -% 5.1% 16.2% 27.7% 39.2%
Wednesday December 16th, 2015 39W, 3D 3.68% 34.46% -% -% 5.6% 17.6% 29.8% 41.7%
Thursday December 17th, 2015 39W, 4D 3.81% 38.21% -% -% 6.2% 19.1% 31.9% 44.2%
Friday December 18th, 2015 39W, 5D 3.91% 42.07% -% -% 6.7% 20.6% 34% 46.7%
Saturday December 19th, 2015 39W, 6D 3.97% 46.02% -% -% 7.4% 22.1% 36.2% 49.2%
Sunday December 20th, 2015 40W, 0D 3.99% 50% -% -% 8% 23.6% 38.3% 51.6%
Monday December 21st, 2015 40W, 1D 3.97% 53.98% -% -% 8.6% 25.1% 40.4% 54%
Tuesday December 22nd, 2015 40W, 2D 3.91% 57.93% -% -% 9.3% 26.7% 42.5% 56.2%
Wednesday December 23rd, 2015 40W, 3D 3.81% 61.79% -% -% 10% 28.2% 44.5% 58.5%
Thursday December 24th, 2015 40W, 4D 3.68% 65.54% -% -% 10.7% 29.8% 46.6% 60.6%
Friday December 25th, 2015 40W, 5D 3.52% 69.15% -% -% 11.4% 31.3% 48.6% 62.7%
Saturday December 26th, 2015 40W, 6D 3.33% 72.57% -% -% 12.1% 32.9% 50.5% 64.7%
Sunday December 27th, 2015 41W, 0D 3.12% 75.8% -% -% 12.9% 34.4% 52.4% 66.6%
Monday December 28th, 2015 41W, 1D 2.9% 78.81% -% -% 13.7% 36% 54.3% 68.5%
Tuesday December 29th, 2015 41W, 2D 2.66% 81.59% -% -% 14.4% 37.5% 56.1% 70.2%
Wednesday December 30th, 2015 41W, 3D 2.42% 84.13% -% -% 15.2% 39% 57.9% 71.9%
Thursday December 31st, 2015 41W, 4D 2.18% 86.43% -% -% 16.1% 40.5% 59.6% 73.5%
Friday January 1st, 2016 41W, 5D 1.94% 88.49% -% -% 16.9% 42% 61.3% 75.1%
Saturday January 2nd, 2016 41W, 6D 1.71% 90.32% -% -% 17.7% 43.4% 62.9% 76.4%
Sunday January 3rd, 2016 42W, 0D 1.5% 91.92% -% -% 18.6% 44.8% 64.5% 77.8%
Monday January 4th, 2016 42W, 1D 1.3% 93.32% -% -% 19.5% 46.3% 65.9% 79.2%
Tuesday January 5th, 2016 42W, 2D 1.11% 94.52% -% -% 20.3% 47.6% 67.3% 80.5%
Wednesday January 6th, 2016 42W, 3D 0.94% 95.54% -% -% 21.1% 48.9% 68.8% 81.6%
Thursday January 7th, 2016 42W, 4D 0.79% 96.41% -% -% 22% 50.1% 70.2% 82.7%
Friday January 8th, 2016 42W, 5D 0.66% 97.13% -% -% 23% 51.6% 71.4% 83.6%
Saturday January 9th, 2016 42W, 6D 0.54% 97.72% -% -% 23.7% 53.1% 72.8% 84.6%
Sunday January 10th, 2016 43W, 0D 0.44% 98.21% -% -% 24.6% 54.2% 73.7% 85.5%
Monday January 11th, 2016 43W, 1D 0.35% 98.61% -% -% 25.2% 55.4% 74.8% 86.3%
Tuesday January 12th, 2016 43W, 2D 0.28% 98.93% -% -% 26.2% 56.1% 75.7% 87.9%
Wednesday January 13th, 2016 43W, 3D 0.22% 99.18% -% -% 26.8% 57.3% 76.8% -%
Thursday January 14th, 2016 43W, 4D 0.18% 99.38% -% -% 29% 58.1% 79% -%
Friday January 15th, 2016 43W, 5D 0.14% 99.53% -% -% 29.8% 59.6% -% -%
Saturday January 16th, 2016 43W, 6D 0.1% 99.65% -% -% 28.6% 62.9% -% -%
Sunday January 17th, 2016 44W, 0D 0.08% 99.74% -% -% 30.8% -% -% -%
Monday January 18th, 2016 44W, 1D 0.06% 99.81% -% -% 31.6% -% -% -%
Tuesday January 19th, 2016 44W, 2D 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.

spacefem's guide to baby-led weaning

Sun Feb 7 10:39 PM by antfancier in Pregnancy & Parenting

Just got back from an infant first aid class. Current guidelines (in the USA) now say you should not use any kind of finger sweep (for adults and infants) - it's better to let the body try to clear the obstruction itself. The only time you intervene is when the airway is completely obstructed and they cannot breathe. But the teacher did say it's hard not to step in when you see your baby gagging, so if you really can't stop yourself then use a finger and thumb 'pincer' rather than a single finger sweep (which poses a higher risk of pushing the obstruction further down the throat).


the unplanned homebirth

Tue Feb 2 11:37 AM by Aum in Pregnancy & Parenting

My great aunt had a baby while on the toilet... but then, she had 19 children in total so I'm sure by baby 10 it wasn't that big of a deal.


High needs newborn support thread

Fri Jan 8 5:12 PM by rowan in Pregnancy & Parenting

One thing I do now that I wish I had done earlier on (though not sure I could have done in the first 6 months due to brain fog), is if I find myself thinking "I wish I could do X" or "I wish I had time for..." even if it's a fleeting thought, I write it down. Well actually I put it in my toodledo list, which I can access on my phone/computer/wherever. Then when I find time I'm like soooo what do I do again? Oh yeah! I wanted to do this thing! I mean, as simple as "read book" or "bake a thing" or something.

Early on though it might be good to look at the list though. Just add things to it. Eventually it gets better and time will come back.


How many sheets/clothes/blankets etc for newborn?

Tue Dec 29 4:41 PM by rowan in Pregnancy & Parenting

^This reminded me, we got two receiving blankets that were made for us, and they were bigger than the little ones that people buy. THOSE were way more useful for much longer.


Vent, advice: How to not be crazy at work...or in general

Wed Nov 4 3:23 PM by Maro in Pregnancy & Parenting

So, my pregnancy hormones are causing me major mood swings right now. I don't necessarily feel ashamed of it, but I'm frustrated enormously by it because I've got a ton of projects at work and a two-year-old to deal with, and I honestly do not have time to sit and cry for 30 minutes every few hours. I really hate being pregnant, for that and other reasons, but right now it's mostly that.

This morning I felt awesome and totally zen and amazing and only vaguely nauseated, and then a couple of things hit at work that I routinely eat for goddamn BREAKFAST and I'm a puddle of tears in my office. Luckily, I work from home so no one can see me, and all I can really do is push through it and keep getting stuff done. But it majorly sucked. Maybe there's no way around it...but if anyone has any ideas for coping with this stuff I'd be grateful. When you Google pregnancy hormones and mood swings the majority of advice is aimed at husbands "surviving" it, which immediately sends me into a rage spiral.


The pregnant woman's business trip from hell (or at least heck)

Sat Feb 6 5:09 PM by lyra211 in Pregnancy & Parenting

Yeah, I went back and checked some sources -- here's the table that I sort of remembered from when I was going through the ectopic scare:
http://www.advancedfertility.com/ectopic.htm
So, half of ectopic pregnancies never get above an hCG level of 1,000, and only 9% ever make it above 10,000. Needless to say, the ones that do keep rising to those very high levels tend to be the scary ones, since those are the ones that keep growing and can cause things like tubal ruptures.

I can't link to it because it's subscriber only, but Up To Date (which has reviews of the most recent medical studies) has the following to say about the hCG threshold of 2,000 (some practices use 1,500 instead) and diagnosis of ectopic pregnancy:

The diagnostic criteria depend upon the relationship to the hCG discriminatory zone (serum hCG level above which a gestational sac should be visualized by TVUS if an IUP is present). The hCG level of the discriminatory zone varies, but in most institutions it is 1500 to 2000 IU/L (see 'Discriminatory zone' above and 'Clinical protocol' above):


not excited about others' pregnancies

Fri Jan 22 8:53 PM by lyra211 in Pregnancy & Parenting

This thread makes me want to make a graph of my excitement levels about other people's pregnancies. It would start off quite mild through teenage years and college, start to spike in early adulthood when I started thinking about maybe being pregnant someday but it was still a distant future possibility, reach a high right around the time my first friends started getting pregnant, drop a little when my husband and I started trying and encountered issues (took us 11 months first time around with my irregular cycles), reach a frenzied crescendo around the time I got pregnant (I was super-excited about being pregnant at the same time as one of my best friends -- we were due with baby girls within a week of each other). Then it dropped like a rock to the depths of deepest despair when our first daughter died at 18w2d in my first pregnancy -- I just couldn't bear to see other pregnant women, especially smug pregnant women who were rubbing their bellies all the time and had the nursery painted by the middle of the second trimester. Now that I'm 36 weeks pregnant with our second, a son, my excitement levels about other people's pregnancies are generally about where they were in teenage/college years, although now tinged with a huge amount of cynicism. Since everyone I know is pregnant at my age, I couldn't care less if someone I know is due within a few weeks of me -- I've been there before. Someone pregnant for the first time and over the moon? I remember feeling that way. It didn't end well. I'm >8 months pregnant, and I still get intensely jealous of first-time pregnant women who have never experienced problems. Heck, I still feel stabs of jealousy when I see other pregnant women rubbing their bellies. I've spent my whole pregnancy mentally keeping my kid at arms' length, not really believing that he's going to be born. I'm still emotional and excited about my pregnancy, but it's all dulled considerably compared to what I felt the first time around -- and I spend much more time worrying and educating myself about potential problems.


Toys that make noises

Wed Jan 6 8:44 PM by melsbells in Pregnancy & Parenting

I definitely don't like these types of toys. I was so grateful when my brother asked how we felt about electronic toys before purchasing one for our kid. Unfortunately, most people don't ask, and even if they know don't care. Our general policy is to not replace batteries when they die, but we haven't caused any to die myteriously. The only batteries we have in the house are attached to a phone, a laptop, and a couple spares for a flashlight.

Just today I heard about this small study on the effects of electronic toys, which didn't really surprise me.

Results Among the 26 parent-infant dyads, toy type was associated with all outcome measures. During play with electronic toys, there were fewer adult words (mean, 39.62; 95% CI, 33.36-45.65), fewer conversational turns (mean, 1.64; 95% CI, 1.12-2.19), fewer parental responses (mean, 1.31; 95% CI, 0.87-1.77), and fewer productions of content-specific words (mean, 1.89; 95% CI, 1.49-2.35) than during play with traditional toys or books.


holiday shopping lists - kids/babies edition!

Mon Dec 14 8:49 PM by ladyhawk in Pregnancy & Parenting

We had something similar happen on the oldest's birthday last year. We had a talk with him about how he was fortunate, and had a lot of things, and asked him to consider sharing with less fortunate kids. He ended up leaving half of them unopened and we took them to the children's hospital.


Childbirth/infant cpr/baby care classes

Mon Nov 2 11:25 PM by antfancier in Pregnancy & Parenting

Thanks everyone! Lots for me to think about...

I have just started prenatal yoga and it seems that it will be pretty useful - although it's way more physical hard work than I expected (I'd better get used to it now, I guess).

Also, I hope I get an inflatable baby from whichever course I end up going with.


Group B Strep

Wed Feb 3 2:02 AM by lyra211 in Pregnancy & Parenting

It's not at my (US) hospital, alas, and I got the impression it is not common. :-( I am just planning to eat a bunch of yogurt and other probiotic stuff after birth and hope for the best (there's apparently some evidence that good bacteria can be passed through breast milk, so hopefully as I rebuild my own microbiome I'll also be helping my baby to build his). I'm simply not willing to take the risks associate with passing up antibiotics, so I think focusing on rebuilding a healthy microbiome is probably the best I can do.


'Forest' preschools

Mon Jan 11 3:21 AM by rowan in Pregnancy & Parenting

It's currently -22 C here and didn't get above -18. The wind was pretty bad too, which makes it worse. *shrug* Brisk activity would have been fine, like sledding or skiing, if it hadn't been for the wind, but trying to actually learn things I think would be much more challenging. Not the least of which is it would damage any equipment you were trying to use. I don't think you could really sustainably do it for the entire winter, or at least not for January and February.


speaker tampon lets you play music to your fetus

Tue Jan 5 5:36 PM by Aum in Pregnancy & Parenting

^ You'd have to pick something like heavy metal or drum & bass. Your kid would turn out all punk as a result, so it's win-win!


disapproving babies

Mon Dec 7 3:04 AM by Bork in Pregnancy & Parenting

I think your baby totally wins the "disapproving baby" contest. Her face is amazing. She's got the eyebrows and the mouth and oh man.


Postpartum girdle?

Fri Oct 23 2:47 PM by rowan in Pregnancy & Parenting

Interesting to hear everyone's stories about recovery. I still have issues with some of my ab muscles, I wonder if it would have helped.