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 4th, 2020.

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
Tuesday June 30th, 2020 35W, 0D 0.01% 0.02% -% -% -% 0.1% 0.1% 0.2%
Wednesday July 1st, 2020 35W, 1D 0.01% 0.03% -% -% -% 0.1% 0.2% 0.3%
Thursday July 2nd, 2020 35W, 2D 0.02% 0.05% -% -% -% 0.1% 0.2% 0.4%
Friday July 3rd, 2020 35W, 3D 0.02% 0.07% -% -% -% 0.1% 0.3% 0.6%
Saturday July 4th, 2020 35W, 4D 0.03% 0.1% -% -% -% 0.2% 0.4% 0.7%
Sunday July 5th, 2020 35W, 5D 0.04% 0.13% -% -% -% 0.2% 0.5% 0.9%
Monday July 6th, 2020 35W, 6D 0.06% 0.19% -% -% 0.1% 0.3% 0.6% 1.2%
Tuesday July 7th, 2020 36W, 0D 0.08% 0.26% -% -% 0.1% 0.4% 0.8% 1.5%
Wednesday July 8th, 2020 36W, 1D 0.1% 0.35% -% -% 0.1% 0.5% 1% 1.9%
Thursday July 9th, 2020 36W, 2D 0.14% 0.47% -% -% 0.1% 0.6% 1.3% 2.4%
Friday July 10th, 2020 36W, 3D 0.18% 0.62% -% -% 0.2% 0.8% 1.7% 3%
Saturday July 11th, 2020 36W, 4D 0.22% 0.82% -% -% 0.2% 1% 2.1% 3.7%
Sunday July 12th, 2020 36W, 5D 0.28% 1.07% -% -% 0.3% 1.2% 2.5% 4.5%
Monday July 13th, 2020 36W, 6D 0.35% 1.39% -% -% 0.4% 1.5% 3.1% 5.4%
Tuesday July 14th, 2020 37W, 0D 0.44% 1.79% -% -% 0.4% 1.8% 3.8% 6.4%
Wednesday July 15th, 2020 37W, 1D 0.54% 2.28% -% -% 0.6% 2.2% 4.5% 7.6%
Thursday July 16th, 2020 37W, 2D 0.66% 2.87% -% -% 0.7% 2.7% 5.4% 8.9%
Friday July 17th, 2020 37W, 3D 0.79% 3.59% -% -% 0.8% 3.2% 6.3% 10.4%
Saturday July 18th, 2020 37W, 4D 0.94% 4.46% -% -% 1% 3.8% 7.4% 11.9%
Sunday July 19th, 2020 37W, 5D 1.11% 5.48% -% -% 1.2% 4.4% 8.6% 13.7%
Monday July 20th, 2020 37W, 6D 1.3% 6.68% -% -% 1.4% 5.2% 9.8% 15.5%
Tuesday July 21st, 2020 38W, 0D 1.5% 8.08% -% -% 1.6% 6% 11.2% 17.5%
Wednesday July 22nd, 2020 38W, 1D 1.71% 9.68% -% -% 1.9% 6.9% 12.7% 19.7%
Thursday July 23rd, 2020 38W, 2D 1.94% 11.51% -% -% 2.2% 7.8% 14.3% 21.9%
Friday July 24th, 2020 38W, 3D 2.18% 13.57% -% -% 2.5% 8.8% 16% 24.2%
Saturday July 25th, 2020 38W, 4D 2.42% 15.87% -% -% 2.9% 9.9% 17.8% 26.6%
Sunday July 26th, 2020 38W, 5D 2.66% 18.41% -% -% 3.3% 11.1% 19.7% 29%
Monday July 27th, 2020 38W, 6D 2.9% 21.19% -% -% 3.7% 12.3% 21.6% 31.5%
Tuesday July 28th, 2020 39W, 0D 3.12% 24.2% -% -% 4.1% 13.5% 23.6% 34%
Wednesday July 29th, 2020 39W, 1D 3.33% 27.43% -% -% 4.6% 14.9% 25.6% 36.6%
Thursday July 30th, 2020 39W, 2D 3.52% 30.85% -% -% 5.1% 16.2% 27.7% 39.2%
Friday July 31st, 2020 39W, 3D 3.68% 34.46% -% -% 5.6% 17.6% 29.8% 41.7%
Saturday August 1st, 2020 39W, 4D 3.81% 38.21% -% -% 6.2% 19.1% 31.9% 44.2%
Sunday August 2nd, 2020 39W, 5D 3.91% 42.07% -% -% 6.7% 20.6% 34% 46.7%
Monday August 3rd, 2020 39W, 6D 3.97% 46.02% -% -% 7.4% 22.1% 36.2% 49.2%
Tuesday August 4th, 2020 40W, 0D 3.99% 50% 8% 0% 8% 23.6% 38.3% 51.6%
Wednesday August 5th, 2020 40W, 1D 3.97% 53.98% 7.9% 8% 8.6% 25.1% 40.4% 54%
Thursday August 6th, 2020 40W, 2D 3.91% 57.93% 7.8% 15.9% 9.3% 26.7% 42.5% 56.2%
Friday August 7th, 2020 40W, 3D 3.81% 61.79% 7.6% 23.6% 10% 28.2% 44.5% 58.5%
Saturday August 8th, 2020 40W, 4D 3.68% 65.54% 7.4% 31.1% 10.7% 29.8% 46.6% 60.6%
Sunday August 9th, 2020 40W, 5D 3.52% 69.15% 7% 38.3% 11.4% 31.3% 48.6% 62.7%
Monday August 10th, 2020 40W, 6D 3.33% 72.57% 6.7% 45.1% 12.1% 32.9% 50.5% 64.7%
Tuesday August 11th, 2020 41W, 0D 3.12% 75.8% 6.2% 51.6% 12.9% 34.4% 52.4% 66.6%
Wednesday August 12th, 2020 41W, 1D 2.9% 78.81% 5.8% 57.6% 13.7% 36% 54.3% 68.5%
Thursday August 13th, 2020 41W, 2D 2.66% 81.59% 5.3% 63.2% 14.4% 37.5% 56.1% 70.2%
Friday August 14th, 2020 41W, 3D 2.42% 84.13% 4.8% 68.3% 15.2% 39% 57.9% 71.9%
Saturday August 15th, 2020 41W, 4D 2.18% 86.43% 4.4% 72.9% 16.1% 40.5% 59.6% 73.5%
Sunday August 16th, 2020 41W, 5D 1.94% 88.49% 3.9% 77% 16.9% 42% 61.3% 75.1%
Monday August 17th, 2020 41W, 6D 1.71% 90.32% 3.4% 80.6% 17.7% 43.4% 62.9% 76.4%
Tuesday August 18th, 2020 42W, 0D 1.5% 91.92% 3% 83.8% 18.6% 44.8% 64.5% 77.8%
Wednesday August 19th, 2020 42W, 1D 1.3% 93.32% 2.6% 86.6% 19.5% 46.3% 65.9% 79.2%
Thursday August 20th, 2020 42W, 2D 1.11% 94.52% 2.2% 89% 20.3% 47.6% 67.3% 80.5%
Friday August 21st, 2020 42W, 3D 0.94% 95.54% 1.9% 91.1% 21.1% 48.9% 68.8% 81.6%
Saturday August 22nd, 2020 42W, 4D 0.79% 96.41% 1.6% 92.8% 22% 50.1% 70.2% 82.7%
Sunday August 23rd, 2020 42W, 5D 0.66% 97.13% 1.3% 94.3% 23% 51.6% 71.4% 83.6%
Monday August 24th, 2020 42W, 6D 0.54% 97.72% 1.1% 95.4% 23.7% 53.1% 72.8% 84.6%
Tuesday August 25th, 2020 43W, 0D 0.44% 98.21% 0.9% 96.4% 24.6% 54.2% 73.7% 85.5%
Wednesday August 26th, 2020 43W, 1D 0.35% 98.61% 0.7% 97.2% 25.2% 55.4% 74.8% 86.3%
Thursday August 27th, 2020 43W, 2D 0.28% 98.93% 0.6% 97.9% 26.2% 56.1% 75.7% 87.9%
Friday August 28th, 2020 43W, 3D 0.22% 99.18% 0.4% 98.4% 26.8% 57.3% 76.8% -%
Saturday August 29th, 2020 43W, 4D 0.18% 99.38% 0.4% 98.8% 29% 58.1% 79% -%
Sunday August 30th, 2020 43W, 5D 0.14% 99.53% 0.3% 99.1% 29.8% 59.6% -% -%
Monday August 31st, 2020 43W, 6D 0.1% 99.65% 0.2% 99.3% 28.6% 62.9% -% -%
Tuesday September 1st, 2020 44W, 0D 0.08% 99.74% 0.2% 99.5% 30.8% -% -% -%
Wednesday September 2nd, 2020 44W, 1D 0.06% 99.81% 0.1% 99.6% 31.6% -% -% -%
Thursday September 3rd, 2020 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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