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 October 27th, 2021.
| 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 | ||
| Wednesday September 22nd, 2021 | 35W, 0D | 0.01% | 0.02% | -% | -% | -% | 0.1% | 0.1% | 0.2% |
| Thursday September 23rd, 2021 | 35W, 1D | 0.01% | 0.03% | -% | -% | -% | 0.1% | 0.2% | 0.3% |
| Friday September 24th, 2021 | 35W, 2D | 0.02% | 0.05% | -% | -% | -% | 0.1% | 0.2% | 0.4% |
| Saturday September 25th, 2021 | 35W, 3D | 0.02% | 0.07% | -% | -% | -% | 0.1% | 0.3% | 0.6% |
| Sunday September 26th, 2021 | 35W, 4D | 0.03% | 0.1% | -% | -% | -% | 0.2% | 0.4% | 0.7% |
| Monday September 27th, 2021 | 35W, 5D | 0.04% | 0.13% | -% | -% | -% | 0.2% | 0.5% | 0.9% |
| Tuesday September 28th, 2021 | 35W, 6D | 0.06% | 0.19% | -% | -% | 0.1% | 0.3% | 0.6% | 1.2% |
| Wednesday September 29th, 2021 | 36W, 0D | 0.08% | 0.26% | -% | -% | 0.1% | 0.4% | 0.8% | 1.5% |
| Thursday September 30th, 2021 | 36W, 1D | 0.1% | 0.35% | -% | -% | 0.1% | 0.5% | 1% | 1.9% |
| Friday October 1st, 2021 | 36W, 2D | 0.14% | 0.47% | -% | -% | 0.1% | 0.6% | 1.3% | 2.4% |
| Saturday October 2nd, 2021 | 36W, 3D | 0.18% | 0.62% | -% | -% | 0.2% | 0.8% | 1.7% | 3% |
| Sunday October 3rd, 2021 | 36W, 4D | 0.22% | 0.82% | -% | -% | 0.2% | 1% | 2.1% | 3.7% |
| Monday October 4th, 2021 | 36W, 5D | 0.28% | 1.07% | -% | -% | 0.3% | 1.2% | 2.5% | 4.5% |
| Tuesday October 5th, 2021 | 36W, 6D | 0.35% | 1.39% | -% | -% | 0.4% | 1.5% | 3.1% | 5.4% |
| Wednesday October 6th, 2021 | 37W, 0D | 0.44% | 1.79% | -% | -% | 0.4% | 1.8% | 3.8% | 6.4% |
| Thursday October 7th, 2021 | 37W, 1D | 0.54% | 2.28% | -% | -% | 0.6% | 2.2% | 4.5% | 7.6% |
| Friday October 8th, 2021 | 37W, 2D | 0.66% | 2.87% | -% | -% | 0.7% | 2.7% | 5.4% | 8.9% |
| Saturday October 9th, 2021 | 37W, 3D | 0.79% | 3.59% | -% | -% | 0.8% | 3.2% | 6.3% | 10.4% |
| Sunday October 10th, 2021 | 37W, 4D | 0.94% | 4.46% | -% | -% | 1% | 3.8% | 7.4% | 11.9% |
| Monday October 11th, 2021 | 37W, 5D | 1.11% | 5.48% | -% | -% | 1.2% | 4.4% | 8.6% | 13.7% |
| Tuesday October 12th, 2021 | 37W, 6D | 1.3% | 6.68% | -% | -% | 1.4% | 5.2% | 9.8% | 15.5% |
| Wednesday October 13th, 2021 | 38W, 0D | 1.5% | 8.08% | -% | -% | 1.6% | 6% | 11.2% | 17.5% |
| Thursday October 14th, 2021 | 38W, 1D | 1.71% | 9.68% | -% | -% | 1.9% | 6.9% | 12.7% | 19.7% |
| Friday October 15th, 2021 | 38W, 2D | 1.94% | 11.51% | -% | -% | 2.2% | 7.8% | 14.3% | 21.9% |
| Saturday October 16th, 2021 | 38W, 3D | 2.18% | 13.57% | -% | -% | 2.5% | 8.8% | 16% | 24.2% |
| Sunday October 17th, 2021 | 38W, 4D | 2.42% | 15.87% | -% | -% | 2.9% | 9.9% | 17.8% | 26.6% |
| Monday October 18th, 2021 | 38W, 5D | 2.66% | 18.41% | -% | -% | 3.3% | 11.1% | 19.7% | 29% |
| Tuesday October 19th, 2021 | 38W, 6D | 2.9% | 21.19% | -% | -% | 3.7% | 12.3% | 21.6% | 31.5% |
| Wednesday October 20th, 2021 | 39W, 0D | 3.12% | 24.2% | -% | -% | 4.1% | 13.5% | 23.6% | 34% |
| Thursday October 21st, 2021 | 39W, 1D | 3.33% | 27.43% | -% | -% | 4.6% | 14.9% | 25.6% | 36.6% |
| Friday October 22nd, 2021 | 39W, 2D | 3.52% | 30.85% | -% | -% | 5.1% | 16.2% | 27.7% | 39.2% |
| Saturday October 23rd, 2021 | 39W, 3D | 3.68% | 34.46% | -% | -% | 5.6% | 17.6% | 29.8% | 41.7% |
| Sunday October 24th, 2021 | 39W, 4D | 3.81% | 38.21% | -% | -% | 6.2% | 19.1% | 31.9% | 44.2% |
| Monday October 25th, 2021 | 39W, 5D | 3.91% | 42.07% | -% | -% | 6.7% | 20.6% | 34% | 46.7% |
| Tuesday October 26th, 2021 | 39W, 6D | 3.97% | 46.02% | -% | -% | 7.4% | 22.1% | 36.2% | 49.2% |
| Wednesday October 27th, 2021 | 40W, 0D | 3.99% | 50% | -% | -% | 8% | 23.6% | 38.3% | 51.6% |
| Thursday October 28th, 2021 | 40W, 1D | 3.97% | 53.98% | -% | -% | 8.6% | 25.1% | 40.4% | 54% |
| Friday October 29th, 2021 | 40W, 2D | 3.91% | 57.93% | -% | -% | 9.3% | 26.7% | 42.5% | 56.2% |
| Saturday October 30th, 2021 | 40W, 3D | 3.81% | 61.79% | -% | -% | 10% | 28.2% | 44.5% | 58.5% |
| Sunday October 31st, 2021 | 40W, 4D | 3.68% | 65.54% | -% | -% | 10.7% | 29.8% | 46.6% | 60.6% |
| Monday November 1st, 2021 | 40W, 5D | 3.52% | 69.15% | -% | -% | 11.4% | 31.3% | 48.6% | 62.7% |
| Tuesday November 2nd, 2021 | 40W, 6D | 3.33% | 72.57% | -% | -% | 12.1% | 32.9% | 50.5% | 64.7% |
| Wednesday November 3rd, 2021 | 41W, 0D | 3.12% | 75.8% | -% | -% | 12.9% | 34.4% | 52.4% | 66.6% |
| Thursday November 4th, 2021 | 41W, 1D | 2.9% | 78.81% | -% | -% | 13.7% | 36% | 54.3% | 68.5% |
| Friday November 5th, 2021 | 41W, 2D | 2.66% | 81.59% | -% | -% | 14.4% | 37.5% | 56.1% | 70.2% |
| Saturday November 6th, 2021 | 41W, 3D | 2.42% | 84.13% | -% | -% | 15.2% | 39% | 57.9% | 71.9% |
| Sunday November 7th, 2021 | 41W, 4D | 2.18% | 86.43% | -% | -% | 16.1% | 40.5% | 59.6% | 73.5% |
| Monday November 8th, 2021 | 41W, 5D | 1.94% | 88.49% | -% | -% | 16.9% | 42% | 61.3% | 75.1% |
| Tuesday November 9th, 2021 | 41W, 6D | 1.71% | 90.32% | -% | -% | 17.7% | 43.4% | 62.9% | 76.4% |
| Wednesday November 10th, 2021 | 42W, 0D | 1.5% | 91.92% | -% | -% | 18.6% | 44.8% | 64.5% | 77.8% |
| Thursday November 11th, 2021 | 42W, 1D | 1.3% | 93.32% | -% | -% | 19.5% | 46.3% | 65.9% | 79.2% |
| Friday November 12th, 2021 | 42W, 2D | 1.11% | 94.52% | -% | -% | 20.3% | 47.6% | 67.3% | 80.5% |
| Saturday November 13th, 2021 | 42W, 3D | 0.94% | 95.54% | -% | -% | 21.1% | 48.9% | 68.8% | 81.6% |
| Sunday November 14th, 2021 | 42W, 4D | 0.79% | 96.41% | -% | -% | 22% | 50.1% | 70.2% | 82.7% |
| Monday November 15th, 2021 | 42W, 5D | 0.66% | 97.13% | -% | -% | 23% | 51.6% | 71.4% | 83.6% |
| Tuesday November 16th, 2021 | 42W, 6D | 0.54% | 97.72% | -% | -% | 23.7% | 53.1% | 72.8% | 84.6% |
| Wednesday November 17th, 2021 | 43W, 0D | 0.44% | 98.21% | -% | -% | 24.6% | 54.2% | 73.7% | 85.5% |
| Thursday November 18th, 2021 | 43W, 1D | 0.35% | 98.61% | -% | -% | 25.2% | 55.4% | 74.8% | 86.3% |
| Friday November 19th, 2021 | 43W, 2D | 0.28% | 98.93% | -% | -% | 26.2% | 56.1% | 75.7% | 87.9% |
| Saturday November 20th, 2021 | 43W, 3D | 0.22% | 99.18% | -% | -% | 26.8% | 57.3% | 76.8% | -% |
| Sunday November 21st, 2021 | 43W, 4D | 0.18% | 99.38% | -% | -% | 29% | 58.1% | 79% | -% |
| Monday November 22nd, 2021 | 43W, 5D | 0.14% | 99.53% | -% | -% | 29.8% | 59.6% | -% | -% |
| Tuesday November 23rd, 2021 | 43W, 6D | 0.1% | 99.65% | -% | -% | 28.6% | 62.9% | -% | -% |
| Wednesday November 24th, 2021 | 44W, 0D | 0.08% | 99.74% | -% | -% | 30.8% | -% | -% | -% |
| Thursday November 25th, 2021 | 44W, 1D | 0.06% | 99.81% | -% | -% | 31.6% | -% | -% | -% |
| Friday November 26th, 2021 | 44W, 2D | 0.04% | 99.87% | -% | -% | 30.8% | -% | -% | -% |
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.