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 July 23rd, 2021.

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 June 18th, 2021 35W, 0D 0.01% 0.02% -% -% -% 0.1% 0.1% 0.2%
Saturday June 19th, 2021 35W, 1D 0.01% 0.03% -% -% -% 0.1% 0.2% 0.3%
Sunday June 20th, 2021 35W, 2D 0.02% 0.05% -% -% -% 0.1% 0.2% 0.4%
Monday June 21st, 2021 35W, 3D 0.02% 0.07% -% -% -% 0.1% 0.3% 0.6%
Tuesday June 22nd, 2021 35W, 4D 0.03% 0.1% -% -% -% 0.2% 0.4% 0.7%
Wednesday June 23rd, 2021 35W, 5D 0.04% 0.13% -% -% -% 0.2% 0.5% 0.9%
Thursday June 24th, 2021 35W, 6D 0.06% 0.19% -% -% 0.1% 0.3% 0.6% 1.2%
Friday June 25th, 2021 36W, 0D 0.08% 0.26% -% -% 0.1% 0.4% 0.8% 1.5%
Saturday June 26th, 2021 36W, 1D 0.1% 0.35% -% -% 0.1% 0.5% 1% 1.9%
Sunday June 27th, 2021 36W, 2D 0.14% 0.47% -% -% 0.1% 0.6% 1.3% 2.4%
Monday June 28th, 2021 36W, 3D 0.18% 0.62% -% -% 0.2% 0.8% 1.7% 3%
Tuesday June 29th, 2021 36W, 4D 0.22% 0.82% -% -% 0.2% 1% 2.1% 3.7%
Wednesday June 30th, 2021 36W, 5D 0.28% 1.07% -% -% 0.3% 1.2% 2.5% 4.5%
Thursday July 1st, 2021 36W, 6D 0.35% 1.39% -% -% 0.4% 1.5% 3.1% 5.4%
Friday July 2nd, 2021 37W, 0D 0.44% 1.79% -% -% 0.4% 1.8% 3.8% 6.4%
Saturday July 3rd, 2021 37W, 1D 0.54% 2.28% -% -% 0.6% 2.2% 4.5% 7.6%
Sunday July 4th, 2021 37W, 2D 0.66% 2.87% -% -% 0.7% 2.7% 5.4% 8.9%
Monday July 5th, 2021 37W, 3D 0.79% 3.59% -% -% 0.8% 3.2% 6.3% 10.4%
Tuesday July 6th, 2021 37W, 4D 0.94% 4.46% -% -% 1% 3.8% 7.4% 11.9%
Wednesday July 7th, 2021 37W, 5D 1.11% 5.48% -% -% 1.2% 4.4% 8.6% 13.7%
Thursday July 8th, 2021 37W, 6D 1.3% 6.68% -% -% 1.4% 5.2% 9.8% 15.5%
Friday July 9th, 2021 38W, 0D 1.5% 8.08% -% -% 1.6% 6% 11.2% 17.5%
Saturday July 10th, 2021 38W, 1D 1.71% 9.68% -% -% 1.9% 6.9% 12.7% 19.7%
Sunday July 11th, 2021 38W, 2D 1.94% 11.51% -% -% 2.2% 7.8% 14.3% 21.9%
Monday July 12th, 2021 38W, 3D 2.18% 13.57% -% -% 2.5% 8.8% 16% 24.2%
Tuesday July 13th, 2021 38W, 4D 2.42% 15.87% -% -% 2.9% 9.9% 17.8% 26.6%
Wednesday July 14th, 2021 38W, 5D 2.66% 18.41% -% -% 3.3% 11.1% 19.7% 29%
Thursday July 15th, 2021 38W, 6D 2.9% 21.19% -% -% 3.7% 12.3% 21.6% 31.5%
Friday July 16th, 2021 39W, 0D 3.12% 24.2% -% -% 4.1% 13.5% 23.6% 34%
Saturday July 17th, 2021 39W, 1D 3.33% 27.43% -% -% 4.6% 14.9% 25.6% 36.6%
Sunday July 18th, 2021 39W, 2D 3.52% 30.85% -% -% 5.1% 16.2% 27.7% 39.2%
Monday July 19th, 2021 39W, 3D 3.68% 34.46% -% -% 5.6% 17.6% 29.8% 41.7%
Tuesday July 20th, 2021 39W, 4D 3.81% 38.21% -% -% 6.2% 19.1% 31.9% 44.2%
Wednesday July 21st, 2021 39W, 5D 3.91% 42.07% -% -% 6.7% 20.6% 34% 46.7%
Thursday July 22nd, 2021 39W, 6D 3.97% 46.02% -% -% 7.4% 22.1% 36.2% 49.2%
Friday July 23rd, 2021 40W, 0D 3.99% 50% -% -% 8% 23.6% 38.3% 51.6%
Saturday July 24th, 2021 40W, 1D 3.97% 53.98% 7.9% 8% 8.6% 25.1% 40.4% 54%
Sunday July 25th, 2021 40W, 2D 3.91% 57.93% 7.8% 15.9% 9.3% 26.7% 42.5% 56.2%
Monday July 26th, 2021 40W, 3D 3.81% 61.79% 7.6% 23.6% 10% 28.2% 44.5% 58.5%
Tuesday July 27th, 2021 40W, 4D 3.68% 65.54% 7.4% 31.1% 10.7% 29.8% 46.6% 60.6%
Wednesday July 28th, 2021 40W, 5D 3.52% 69.15% 7% 38.3% 11.4% 31.3% 48.6% 62.7%
Thursday July 29th, 2021 40W, 6D 3.33% 72.57% 6.7% 45.1% 12.1% 32.9% 50.5% 64.7%
Friday July 30th, 2021 41W, 0D 3.12% 75.8% 6.2% 51.6% 12.9% 34.4% 52.4% 66.6%
Saturday July 31st, 2021 41W, 1D 2.9% 78.81% 5.8% 57.6% 13.7% 36% 54.3% 68.5%
Sunday August 1st, 2021 41W, 2D 2.66% 81.59% 5.3% 63.2% 14.4% 37.5% 56.1% 70.2%
Monday August 2nd, 2021 41W, 3D 2.42% 84.13% 4.8% 68.3% 15.2% 39% 57.9% 71.9%
Tuesday August 3rd, 2021 41W, 4D 2.18% 86.43% 4.4% 72.9% 16.1% 40.5% 59.6% 73.5%
Wednesday August 4th, 2021 41W, 5D 1.94% 88.49% 3.9% 77% 16.9% 42% 61.3% 75.1%
Thursday August 5th, 2021 41W, 6D 1.71% 90.32% 3.4% 80.6% 17.7% 43.4% 62.9% 76.4%
Friday August 6th, 2021 42W, 0D 1.5% 91.92% 3% 83.8% 18.6% 44.8% 64.5% 77.8%
Saturday August 7th, 2021 42W, 1D 1.3% 93.32% 2.6% 86.6% 19.5% 46.3% 65.9% 79.2%
Sunday August 8th, 2021 42W, 2D 1.11% 94.52% 2.2% 89% 20.3% 47.6% 67.3% 80.5%
Monday August 9th, 2021 42W, 3D 0.94% 95.54% 1.9% 91.1% 21.1% 48.9% 68.8% 81.6%
Tuesday August 10th, 2021 42W, 4D 0.79% 96.41% 1.6% 92.8% 22% 50.1% 70.2% 82.7%
Wednesday August 11th, 2021 42W, 5D 0.66% 97.13% 1.3% 94.3% 23% 51.6% 71.4% 83.6%
Thursday August 12th, 2021 42W, 6D 0.54% 97.72% 1.1% 95.4% 23.7% 53.1% 72.8% 84.6%
Friday August 13th, 2021 43W, 0D 0.44% 98.21% 0.9% 96.4% 24.6% 54.2% 73.7% 85.5%
Saturday August 14th, 2021 43W, 1D 0.35% 98.61% 0.7% 97.2% 25.2% 55.4% 74.8% 86.3%
Sunday August 15th, 2021 43W, 2D 0.28% 98.93% 0.6% 97.9% 26.2% 56.1% 75.7% 87.9%
Monday August 16th, 2021 43W, 3D 0.22% 99.18% 0.4% 98.4% 26.8% 57.3% 76.8% -%
Tuesday August 17th, 2021 43W, 4D 0.18% 99.38% 0.4% 98.8% 29% 58.1% 79% -%
Wednesday August 18th, 2021 43W, 5D 0.14% 99.53% 0.3% 99.1% 29.8% 59.6% -% -%
Thursday August 19th, 2021 43W, 6D 0.1% 99.65% 0.2% 99.3% 28.6% 62.9% -% -%
Friday August 20th, 2021 44W, 0D 0.08% 99.74% 0.2% 99.5% 30.8% -% -% -%
Saturday August 21st, 2021 44W, 1D 0.06% 99.81% 0.1% 99.6% 31.6% -% -% -%
Sunday August 22nd, 2021 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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