Displays the overall probability of miscarriage - or, conversely, the probability of birth - based on pregnancy length by day and maternal history.

Move your mouse over the graph to highlight the specific odds. |
Chart Mode |

Nervous about miscarriage? Let us reassure you.

Knowing doesn't have to be scary. The Daily Miscarriage Probability Chart calculates the probability of miscarriage or, conversly, the probability of birth, given how far a woman is in her pregnancy. The underlying model can also account for added risk factors like maternal age, weight, the number of previous miscarriages and the number of previous live births.

The miscarriage probability graph displays the probability of a miscarriage occuring on or after a given point in pregnancy. You can therefore find the day-specific odds, or the odds between two points in time, by subtracting the probability associated with date from another. For example, if the model gives the probability of miscarriage on or after 4 weeks, 0 days is as 25.2%, and the probability of miscarriage on or after 4 weeks, 1 day as 24.4%, then the probability of miscarriage occuring on exactly 4 weeks, 0 days is 25.2-24.4 or 0.8%. Probabilities in the graph are rounded to the nearest tenth of a percent, so very small probability differences between two dates may not be noticable in the graph.

**Take the Probabilities With You**

Want to bookmark the Miscarriage Probability Chart with all it's data so you don't have to keep re-entering your maternal info it day after day?

Click here to get a paramterized URL.

**About the model** Miscarriage is generally recognized
as pregnancy loss before 20 weeks gestation. This page calculates the cumulative
probability of pregnancy loss from a given point in pregnancy through 20 weeks gestation. Beyond 20 weeks gestation pregnancy
most often ends in a live birth, and rarely in still birth. Thus, we refer to the probability of not miscarring as the
probability of birth.

The underlying model for this site is derived using meta analysis of the following peer reviewed papers on miscarriage. The model can be be used without additional input, or can be adjusted with any combination of maternal age, height/weight (BMI), number of previous miscarriages and number of previous births inputs. Each variable is modeled separately, assumed to be independent and assumed to affect the probability of miscarriage uniformly over time. These assumptions are likely overly strong, as there are likely counfounding variables, but is the most reasonable approximation in the absense of additional data.

- [1] Tong, S., Kaur, A., Walker, S. P., Bryant, V., Onwude, J. L., and Permezel, M. (2008), Miscarriage Risk for Asymptomatic Women After a Normal First-Trimester Prenatal Visit. Obstetrics & Gynecology: March 2008 - Volume 111 - Issue 3 - pp 710-714 doi: 10.1097/AOG.0b013e318163747c
- [2] Wang, J. X., Davies, M. J. and Norman, R. J. (2002), Obesity Increases the Risk of Spontaneous Abortion during Infertility Treatment. Obesity Research, 10: 551–554. doi: 10.1038/oby.2002.74
- [3] Maconochie, N., Doyle, P., Prior, S. and Simmons, R. (2007), Risk factors for first trimester miscarriage—results from a UK-population-based case–control study. BJOG: An International Journal of Obstetrics & Gynaecology, 114: 170–186. doi: 10.1111/j.1471-0528.2006.01193.x
- [4]
Avalos, L. A., Galindo, C., Li, D. (2012) A systematic review to calculate background miscarriage rates using life table analysis.
Birth Defects Research Part A: Clinical and Molecular Teratology
Volume 94, Issue 6. pages 417–423. doi: 10.1002/bdra.23014

- Including cited studies, Taylor (1970), Harlap et al (1980), Goldhaber and Fireman (1991), and Li et al (2002) - [5] Mukherjee, S., Velez Edwards, D. R., Baird, D. D., Savitz, D. A., Hartmann, K. E.; (2013) Risk of Miscarriage Among Black Women and White Women in a US Prospective Cohort Study. Am J Epidemiol 2013; 177 (11): 1271-1278. doi: 10.1093/aje/kws393

Results from multiple studies are weighted differently depending on the number of participents included in the study, demographics of the study participents and study methodology.

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Model Update 2/25/17: In an effort to give you the most accurate information possible, we incorporated several additional, large scale studies into our model: Avalos et al [4] and Mukharjee et al [5]. These new studies contain over 50,000 participents combined. Consequently, the estimated probability of miscarriaged associated with many gestational ages have changed, some significantly, and some increased. The largest differences are between 6 and 9 weeks gestation. Please feel free to contact me with any questions about how the updated model was derived or how the updated model differs from the previous one.I know that early pregnancy can be a time of heightened anxiety, and seeing an increased probability of miscarriage than one is used to may cause alarm. Please remember that the probability of miscarriage is still low, and your pregnancy is still more likely to end with a birth than in miscarriage. If you find your anxiety level increasing, the Miscarriage Reassurer may be able to help alleviate any increased fears.

*This website is intended for informational & entertainment purposes only.
This website is not intended to be considered medical advice.*

**Pregnant?** You may enjoy our other pregnancy apps like the Miscarriage Reassurer or the Personalized Week by Week Calander. When you are a little further along in your pregnancy, be sure to check out the Labor Probability Calculator and Labor Probability Chart.

**Into Probability Distributions?** You may also be interested in our Labor Probability Chart, which charts the probability of labor over time using a left skewed normal distribution.

**Wanting to become pregnant?** Our Time to Conception Calculator
can estimate how long it may take.