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, 2012.
| Date | Progress | Overall odds of spontaneous labor |
Current odds of spontaneous labor |
Odds 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 | ||
| Thursday November 15th, 2012 | 35W, 0D | 0.01% | 0.02% | -% | -% | -% | 0.1% | 0.1% | 0.2% |
| Friday November 16th, 2012 | 35W, 1D | 0.01% | 0.03% | -% | -% | -% | 0.1% | 0.2% | 0.3% |
| Saturday November 17th, 2012 | 35W, 2D | 0.02% | 0.05% | -% | -% | -% | 0.1% | 0.2% | 0.4% |
| Sunday November 18th, 2012 | 35W, 3D | 0.02% | 0.07% | -% | -% | -% | 0.1% | 0.3% | 0.6% |
| Monday November 19th, 2012 | 35W, 4D | 0.03% | 0.1% | -% | -% | -% | 0.2% | 0.4% | 0.7% |
| Tuesday November 20th, 2012 | 35W, 5D | 0.04% | 0.13% | -% | -% | -% | 0.2% | 0.5% | 0.9% |
| Wednesday November 21st, 2012 | 35W, 6D | 0.06% | 0.19% | -% | -% | 0.1% | 0.3% | 0.6% | 1.2% |
| Thursday November 22nd, 2012 | 36W, 0D | 0.08% | 0.26% | -% | -% | 0.1% | 0.4% | 0.8% | 1.5% |
| Friday November 23rd, 2012 | 36W, 1D | 0.1% | 0.35% | -% | -% | 0.1% | 0.5% | 1% | 1.9% |
| Saturday November 24th, 2012 | 36W, 2D | 0.14% | 0.47% | -% | -% | 0.1% | 0.6% | 1.3% | 2.4% |
| Sunday November 25th, 2012 | 36W, 3D | 0.18% | 0.62% | -% | -% | 0.2% | 0.8% | 1.7% | 3% |
| Monday November 26th, 2012 | 36W, 4D | 0.22% | 0.82% | -% | -% | 0.2% | 1% | 2.1% | 3.7% |
| Tuesday November 27th, 2012 | 36W, 5D | 0.28% | 1.07% | -% | -% | 0.3% | 1.2% | 2.5% | 4.5% |
| Wednesday November 28th, 2012 | 36W, 6D | 0.35% | 1.39% | -% | -% | 0.4% | 1.5% | 3.1% | 5.4% |
| Thursday November 29th, 2012 | 37W, 0D | 0.44% | 1.79% | -% | -% | 0.4% | 1.8% | 3.8% | 6.4% |
| Friday November 30th, 2012 | 37W, 1D | 0.54% | 2.28% | -% | -% | 0.6% | 2.2% | 4.5% | 7.6% |
| Saturday December 1st, 2012 | 37W, 2D | 0.66% | 2.87% | -% | -% | 0.7% | 2.7% | 5.4% | 8.9% |
| Sunday December 2nd, 2012 | 37W, 3D | 0.79% | 3.59% | -% | -% | 0.8% | 3.2% | 6.3% | 10.4% |
| Monday December 3rd, 2012 | 37W, 4D | 0.94% | 4.46% | -% | -% | 1% | 3.8% | 7.4% | 11.9% |
| Tuesday December 4th, 2012 | 37W, 5D | 1.11% | 5.48% | -% | -% | 1.2% | 4.4% | 8.6% | 13.7% |
| Wednesday December 5th, 2012 | 37W, 6D | 1.3% | 6.68% | -% | -% | 1.4% | 5.2% | 9.8% | 15.5% |
| Thursday December 6th, 2012 | 38W, 0D | 1.5% | 8.08% | -% | -% | 1.6% | 6% | 11.2% | 17.5% |
| Friday December 7th, 2012 | 38W, 1D | 1.71% | 9.68% | -% | -% | 1.9% | 6.9% | 12.7% | 19.7% |
| Saturday December 8th, 2012 | 38W, 2D | 1.94% | 11.51% | -% | -% | 2.2% | 7.8% | 14.3% | 21.9% |
| Sunday December 9th, 2012 | 38W, 3D | 2.18% | 13.57% | -% | -% | 2.5% | 8.8% | 16% | 24.2% |
| Monday December 10th, 2012 | 38W, 4D | 2.42% | 15.87% | -% | -% | 2.9% | 9.9% | 17.8% | 26.6% |
| Tuesday December 11th, 2012 | 38W, 5D | 2.66% | 18.41% | -% | -% | 3.3% | 11.1% | 19.7% | 29% |
| Wednesday December 12th, 2012 | 38W, 6D | 2.9% | 21.19% | -% | -% | 3.7% | 12.3% | 21.6% | 31.5% |
| Thursday December 13th, 2012 | 39W, 0D | 3.12% | 24.2% | -% | -% | 4.1% | 13.5% | 23.6% | 34% |
| Friday December 14th, 2012 | 39W, 1D | 3.33% | 27.43% | -% | -% | 4.6% | 14.9% | 25.6% | 36.6% |
| Saturday December 15th, 2012 | 39W, 2D | 3.52% | 30.85% | -% | -% | 5.1% | 16.2% | 27.7% | 39.2% |
| Sunday December 16th, 2012 | 39W, 3D | 3.68% | 34.46% | -% | -% | 5.6% | 17.6% | 29.8% | 41.7% |
| Monday December 17th, 2012 | 39W, 4D | 3.81% | 38.21% | -% | -% | 6.2% | 19.1% | 31.9% | 44.2% |
| Tuesday December 18th, 2012 | 39W, 5D | 3.91% | 42.07% | -% | -% | 6.7% | 20.6% | 34% | 46.7% |
| Wednesday December 19th, 2012 | 39W, 6D | 3.97% | 46.02% | -% | -% | 7.4% | 22.1% | 36.2% | 49.2% |
| Thursday December 20th, 2012 | 40W, 0D | 3.99% | 50% | -% | -% | 8% | 23.6% | 38.3% | 51.6% |
| Friday December 21st, 2012 | 40W, 1D | 3.97% | 53.98% | -% | -% | 8.6% | 25.1% | 40.4% | 54% |
| Saturday December 22nd, 2012 | 40W, 2D | 3.91% | 57.93% | -% | -% | 9.3% | 26.7% | 42.5% | 56.2% |
| Sunday December 23rd, 2012 | 40W, 3D | 3.81% | 61.79% | -% | -% | 10% | 28.2% | 44.5% | 58.5% |
| Monday December 24th, 2012 | 40W, 4D | 3.68% | 65.54% | -% | -% | 10.7% | 29.8% | 46.6% | 60.6% |
| Tuesday December 25th, 2012 | 40W, 5D | 3.52% | 69.15% | -% | -% | 11.4% | 31.3% | 48.6% | 62.7% |
| Wednesday December 26th, 2012 | 40W, 6D | 3.33% | 72.57% | -% | -% | 12.1% | 32.9% | 50.5% | 64.7% |
| Thursday December 27th, 2012 | 41W, 0D | 3.12% | 75.8% | -% | -% | 12.9% | 34.4% | 52.4% | 66.6% |
| Friday December 28th, 2012 | 41W, 1D | 2.9% | 78.81% | -% | -% | 13.7% | 36% | 54.3% | 68.5% |
| Saturday December 29th, 2012 | 41W, 2D | 2.66% | 81.59% | -% | -% | 14.4% | 37.5% | 56.1% | 70.2% |
| Sunday December 30th, 2012 | 41W, 3D | 2.42% | 84.13% | -% | -% | 15.2% | 39% | 57.9% | 71.9% |
| Monday December 31st, 2012 | 41W, 4D | 2.18% | 86.43% | -% | -% | 16.1% | 40.5% | 59.6% | 73.5% |
| Tuesday January 1st, 2013 | 41W, 5D | 1.94% | 88.49% | -% | -% | 16.9% | 42% | 61.3% | 75.1% |
| Wednesday January 2nd, 2013 | 41W, 6D | 1.71% | 90.32% | -% | -% | 17.7% | 43.4% | 62.9% | 76.4% |
| Thursday January 3rd, 2013 | 42W, 0D | 1.5% | 91.92% | -% | -% | 18.6% | 44.8% | 64.5% | 77.8% |
| Friday January 4th, 2013 | 42W, 1D | 1.3% | 93.32% | -% | -% | 19.5% | 46.3% | 65.9% | 79.2% |
| Saturday January 5th, 2013 | 42W, 2D | 1.11% | 94.52% | -% | -% | 20.3% | 47.6% | 67.3% | 80.5% |
| Sunday January 6th, 2013 | 42W, 3D | 0.94% | 95.54% | -% | -% | 21.1% | 48.9% | 68.8% | 81.6% |
| Monday January 7th, 2013 | 42W, 4D | 0.79% | 96.41% | -% | -% | 22% | 50.1% | 70.2% | 82.7% |
| Tuesday January 8th, 2013 | 42W, 5D | 0.66% | 97.13% | -% | -% | 23% | 51.6% | 71.4% | 83.6% |
| Wednesday January 9th, 2013 | 42W, 6D | 0.54% | 97.72% | -% | -% | 23.7% | 53.1% | 72.8% | 84.6% |
| Thursday January 10th, 2013 | 43W, 0D | 0.44% | 98.21% | -% | -% | 24.6% | 54.2% | 73.7% | 85.5% |
| Friday January 11th, 2013 | 43W, 1D | 0.35% | 98.61% | -% | -% | 25.2% | 55.4% | 74.8% | 86.3% |
| Saturday January 12th, 2013 | 43W, 2D | 0.28% | 98.93% | -% | -% | 26.2% | 56.1% | 75.7% | 87.9% |
| Sunday January 13th, 2013 | 43W, 3D | 0.22% | 99.18% | -% | -% | 26.8% | 57.3% | 76.8% | -% |
| Monday January 14th, 2013 | 43W, 4D | 0.18% | 99.38% | -% | -% | 29% | 58.1% | 79% | -% |
| Tuesday January 15th, 2013 | 43W, 5D | 0.14% | 99.53% | -% | -% | 29.8% | 59.6% | -% | -% |
| Wednesday January 16th, 2013 | 43W, 6D | 0.1% | 99.65% | -% | -% | 28.6% | 62.9% | -% | -% |
| Thursday January 17th, 2013 | 44W, 0D | 0.08% | 99.74% | -% | -% | 30.8% | -% | -% | -% |
| Friday January 18th, 2013 | 44W, 1D | 0.06% | 99.81% | -% | -% | 31.6% | -% | -% | -% |
| Saturday January 19th, 2013 | 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 odds 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.