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 January 28th, 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 December 24th, 2019 35W, 0D 0.01% 0.02% -% -% -% 0.1% 0.1% 0.2%
Wednesday December 25th, 2019 35W, 1D 0.01% 0.03% -% -% -% 0.1% 0.2% 0.3%
Thursday December 26th, 2019 35W, 2D 0.02% 0.05% -% -% -% 0.1% 0.2% 0.4%
Friday December 27th, 2019 35W, 3D 0.02% 0.07% -% -% -% 0.1% 0.3% 0.6%
Saturday December 28th, 2019 35W, 4D 0.03% 0.1% -% -% -% 0.2% 0.4% 0.7%
Sunday December 29th, 2019 35W, 5D 0.04% 0.13% -% -% -% 0.2% 0.5% 0.9%
Monday December 30th, 2019 35W, 6D 0.06% 0.19% -% -% 0.1% 0.3% 0.6% 1.2%
Tuesday December 31st, 2019 36W, 0D 0.08% 0.26% -% -% 0.1% 0.4% 0.8% 1.5%
Wednesday January 1st, 2020 36W, 1D 0.1% 0.35% -% -% 0.1% 0.5% 1% 1.9%
Thursday January 2nd, 2020 36W, 2D 0.14% 0.47% -% -% 0.1% 0.6% 1.3% 2.4%
Friday January 3rd, 2020 36W, 3D 0.18% 0.62% -% -% 0.2% 0.8% 1.7% 3%
Saturday January 4th, 2020 36W, 4D 0.22% 0.82% -% -% 0.2% 1% 2.1% 3.7%
Sunday January 5th, 2020 36W, 5D 0.28% 1.07% -% -% 0.3% 1.2% 2.5% 4.5%
Monday January 6th, 2020 36W, 6D 0.35% 1.39% -% -% 0.4% 1.5% 3.1% 5.4%
Tuesday January 7th, 2020 37W, 0D 0.44% 1.79% -% -% 0.4% 1.8% 3.8% 6.4%
Wednesday January 8th, 2020 37W, 1D 0.54% 2.28% -% -% 0.6% 2.2% 4.5% 7.6%
Thursday January 9th, 2020 37W, 2D 0.66% 2.87% -% -% 0.7% 2.7% 5.4% 8.9%
Friday January 10th, 2020 37W, 3D 0.79% 3.59% -% -% 0.8% 3.2% 6.3% 10.4%
Saturday January 11th, 2020 37W, 4D 0.94% 4.46% -% -% 1% 3.8% 7.4% 11.9%
Sunday January 12th, 2020 37W, 5D 1.11% 5.48% -% -% 1.2% 4.4% 8.6% 13.7%
Monday January 13th, 2020 37W, 6D 1.3% 6.68% -% -% 1.4% 5.2% 9.8% 15.5%
Tuesday January 14th, 2020 38W, 0D 1.5% 8.08% -% -% 1.6% 6% 11.2% 17.5%
Wednesday January 15th, 2020 38W, 1D 1.71% 9.68% -% -% 1.9% 6.9% 12.7% 19.7%
Thursday January 16th, 2020 38W, 2D 1.94% 11.51% -% -% 2.2% 7.8% 14.3% 21.9%
Friday January 17th, 2020 38W, 3D 2.18% 13.57% -% -% 2.5% 8.8% 16% 24.2%
Saturday January 18th, 2020 38W, 4D 2.42% 15.87% -% -% 2.9% 9.9% 17.8% 26.6%
Sunday January 19th, 2020 38W, 5D 2.66% 18.41% -% -% 3.3% 11.1% 19.7% 29%
Monday January 20th, 2020 38W, 6D 2.9% 21.19% -% -% 3.7% 12.3% 21.6% 31.5%
Tuesday January 21st, 2020 39W, 0D 3.12% 24.2% -% -% 4.1% 13.5% 23.6% 34%
Wednesday January 22nd, 2020 39W, 1D 3.33% 27.43% -% -% 4.6% 14.9% 25.6% 36.6%
Thursday January 23rd, 2020 39W, 2D 3.52% 30.85% -% -% 5.1% 16.2% 27.7% 39.2%
Friday January 24th, 2020 39W, 3D 3.68% 34.46% -% -% 5.6% 17.6% 29.8% 41.7%
Saturday January 25th, 2020 39W, 4D 3.81% 38.21% -% -% 6.2% 19.1% 31.9% 44.2%
Sunday January 26th, 2020 39W, 5D 3.91% 42.07% -% -% 6.7% 20.6% 34% 46.7%
Monday January 27th, 2020 39W, 6D 3.97% 46.02% -% -% 7.4% 22.1% 36.2% 49.2%
Tuesday January 28th, 2020 40W, 0D 3.99% 50% -% -% 8% 23.6% 38.3% 51.6%
Wednesday January 29th, 2020 40W, 1D 3.97% 53.98% 7.9% 8% 8.6% 25.1% 40.4% 54%
Thursday January 30th, 2020 40W, 2D 3.91% 57.93% 7.8% 15.9% 9.3% 26.7% 42.5% 56.2%
Friday January 31st, 2020 40W, 3D 3.81% 61.79% 7.6% 23.6% 10% 28.2% 44.5% 58.5%
Saturday February 1st, 2020 40W, 4D 3.68% 65.54% 7.4% 31.1% 10.7% 29.8% 46.6% 60.6%
Sunday February 2nd, 2020 40W, 5D 3.52% 69.15% 7% 38.3% 11.4% 31.3% 48.6% 62.7%
Monday February 3rd, 2020 40W, 6D 3.33% 72.57% 6.7% 45.1% 12.1% 32.9% 50.5% 64.7%
Tuesday February 4th, 2020 41W, 0D 3.12% 75.8% 6.2% 51.6% 12.9% 34.4% 52.4% 66.6%
Wednesday February 5th, 2020 41W, 1D 2.9% 78.81% 5.8% 57.6% 13.7% 36% 54.3% 68.5%
Thursday February 6th, 2020 41W, 2D 2.66% 81.59% 5.3% 63.2% 14.4% 37.5% 56.1% 70.2%
Friday February 7th, 2020 41W, 3D 2.42% 84.13% 4.8% 68.3% 15.2% 39% 57.9% 71.9%
Saturday February 8th, 2020 41W, 4D 2.18% 86.43% 4.4% 72.9% 16.1% 40.5% 59.6% 73.5%
Sunday February 9th, 2020 41W, 5D 1.94% 88.49% 3.9% 77% 16.9% 42% 61.3% 75.1%
Monday February 10th, 2020 41W, 6D 1.71% 90.32% 3.4% 80.6% 17.7% 43.4% 62.9% 76.4%
Tuesday February 11th, 2020 42W, 0D 1.5% 91.92% 3% 83.8% 18.6% 44.8% 64.5% 77.8%
Wednesday February 12th, 2020 42W, 1D 1.3% 93.32% 2.6% 86.6% 19.5% 46.3% 65.9% 79.2%
Thursday February 13th, 2020 42W, 2D 1.11% 94.52% 2.2% 89% 20.3% 47.6% 67.3% 80.5%
Friday February 14th, 2020 42W, 3D 0.94% 95.54% 1.9% 91.1% 21.1% 48.9% 68.8% 81.6%
Saturday February 15th, 2020 42W, 4D 0.79% 96.41% 1.6% 92.8% 22% 50.1% 70.2% 82.7%
Sunday February 16th, 2020 42W, 5D 0.66% 97.13% 1.3% 94.3% 23% 51.6% 71.4% 83.6%
Monday February 17th, 2020 42W, 6D 0.54% 97.72% 1.1% 95.4% 23.7% 53.1% 72.8% 84.6%
Tuesday February 18th, 2020 43W, 0D 0.44% 98.21% 0.9% 96.4% 24.6% 54.2% 73.7% 85.5%
Wednesday February 19th, 2020 43W, 1D 0.35% 98.61% 0.7% 97.2% 25.2% 55.4% 74.8% 86.3%
Thursday February 20th, 2020 43W, 2D 0.28% 98.93% 0.6% 97.9% 26.2% 56.1% 75.7% 87.9%
Friday February 21st, 2020 43W, 3D 0.22% 99.18% 0.4% 98.4% 26.8% 57.3% 76.8% -%
Saturday February 22nd, 2020 43W, 4D 0.18% 99.38% 0.4% 98.8% 29% 58.1% 79% -%
Sunday February 23rd, 2020 43W, 5D 0.14% 99.53% 0.3% 99.1% 29.8% 59.6% -% -%
Monday February 24th, 2020 43W, 6D 0.1% 99.65% 0.2% 99.3% 28.6% 62.9% -% -%
Tuesday February 25th, 2020 44W, 0D 0.08% 99.74% 0.2% 99.5% 30.8% -% -% -%
Wednesday February 26th, 2020 44W, 1D 0.06% 99.81% 0.1% 99.6% 31.6% -% -% -%
Thursday February 27th, 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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