Miscarriage Calculator: Estimate Pregnancy Loss Risk
Enter your pregnancy details and selected risk factors to receive an estimated miscarriage risk for your current stage.
What This Tool Does
Enter your maternal age, current pregnancy week, previous miscarriage history, smoking or alcohol use, and known medical conditions. This miscarriage risk calculator processes these details and provides an estimated miscarriage risk with a Low, Moderate, or High result for general statistical context.
Miscarriage Calculator
Explore statistical miscarriage-risk context using pregnancy week, maternal age, and selected risk factors.
Enter the information available to you and calculate a general statistical risk context. You can then test different pregnancy-week and age scenarios to see how the displayed context changes.
Enter Your Details
Risk Assessment Results
Enter your details above to see your statistical risk context.
What If?
Explore how the displayed context changes when you compare pregnancy weeks or age references.
Compare Scenarios
Save up to three scenarios from the current page session to compare their inputs and results.
Calculate a result first, then add it here to compare it with another valid scenario.
Scenarios remain only in this page session and are cleared when the page is refreshed or reset.
Understanding the Result
The displayed result combines the calculator inputs with population-level reference context. It is not a diagnosis and cannot predict the outcome of an individual pregnancy.
Maternal age is represented through age-based reference ranges, while pregnancy week is shown as an additional progression context. Previous miscarriage history, lifestyle choices, and selected medical conditions are retained as user context but are not assigned unverified numerical multipliers.
Miscarriage Calculator: Estimate Pregnancy Loss Risk by Week
A miscarriage calculator can help put pregnancy-loss statistics into context using factors such as maternal age and gestational week. This page explains what the SooperTools calculator currently shows, how its reference information is interpreted, and why an online result should not be treated as an individual prediction or diagnosis.
Quick Answer
Miscarriage risk is not one fixed percentage for every pregnancy. ACOG states that early pregnancy loss occurs in about 10% of known pregnancies, and that the frequency increases with maternal age. In its clinical guidance, ACOG reports a frequency of about 9–17% for women aged 20–30, rising to approximately 20% at age 35, 40% at age 40, and 80% at age 45.
The SooperTools calculator should therefore be understood as a statistical reference tool. Its current interface presents age-based risk context and pregnancy-week context rather than claiming to predict exactly what will happen in an individual pregnancy.
What Does the Miscarriage Calculator Show?
The calculator asks for maternal age, current pregnancy week, previous miscarriage history, selected lifestyle factors, and a known medical condition. After calculation, it presents two main pieces of information: an age-based reference context and a pregnancy-week context.
This distinction is important. The current tool does not have a validated combined clinical model that converts every selected input into a personalized percentage. Previous miscarriage history, smoking, alcohol consumption, and a selected medical condition are displayed as context, but the current component does not assign them invented numerical multipliers.
How the Calculation Works
There is no single universal formula that can accurately predict an individual's miscarriage risk from a few online inputs. Published estimates depend on the population studied, gestational age, inclusion criteria, and whether specific clinical findings were present.
The current SooperTools implementation uses two evidence-informed reference layers:
| Input | How the Tool Uses It |
|---|---|
| Maternal age | Mapped to age-based population reference ranges derived from ACOG guidance. |
| Pregnancy week | Used to provide pregnancy-stage context and explain the general trend in risk as gestation advances. |
| Previous miscarriage history | Displayed as selected user context. It is not converted into an unverified numerical adjustment. |
| Smoking or alcohol consumption | Displayed as selected context. No numerical multiplier is applied by the current tool. |
| Known medical condition | Displayed as selected context. No numerical multiplier is applied by the current tool. |
ACOG identifies advanced maternal age and prior early pregnancy loss among the important risk factors associated with early pregnancy loss.
Miscarriage Risk by Maternal Age
Maternal age has a strong association with miscarriage risk. The following reference points are used by the calculator to provide statistical context rather than to predict an individual outcome. ACOG reports 9–17% for ages 20–30, approximately 20% at age 35, 40% at age 40, and 80% at age 45.
| Maternal Age | Reference Context |
|---|---|
| 20–30 | About 9–17% |
| 31–34 | Between the younger-adult and age-35 reference points |
| 35 | About 20% |
| 36–39 | Between about 20% and 40% |
| 40 | About 40% |
| 41–44 | Between about 40% and 80% |
| 45+ | Includes the approximately 80% reference reported for age 45 |
These figures describe population-level frequencies and should not be read as a personal forecast. The exact risk for a particular pregnancy depends on more information than age alone.
How Does Miscarriage Risk Change by Pregnancy Week?
Gestational age is another important part of miscarriage-risk interpretation. In general, the risk of miscarriage decreases as pregnancy progresses, but the exact estimate depends on the study population and clinical circumstances.
A prospective cohort study of 696 asymptomatic women with singleton pregnancies and confirmed fetal cardiac activity found that observed miscarriage risk fell as gestational age advanced. The study reported 9.4% at 6 completed weeks, 4.2% at 7 weeks, 1.5% at 8 weeks, 0.5% at 9 weeks, and 0.7% at 10 weeks. These findings applied specifically to the study population and should not be generalized to every pregnancy.
The SooperTools calculator uses pregnancy week to show this general progression. It does not claim that every person at the same week has the same probability.
What Does a Previous Miscarriage Mean for Risk?
A previous miscarriage is an important part of pregnancy history. ACOG identifies prior early pregnancy loss as one of the common risk factors associated with subsequent early pregnancy loss.
The calculator records whether there were no previous miscarriages, one, two, or three or more. This helps the result describe the user's context, but the current tool does not apply a specific numerical increase to the displayed result because a validated combined equation has not been established for this implementation.
For a broader explanation of miscarriage risk factors and pregnancy-loss statistics, see the SooperTools miscarriage risk guide.
Does a Heartbeat Change Miscarriage Risk?
Fetal cardiac activity can be clinically important when evaluating an early pregnancy. Research has found that, among specific groups of asymptomatic women with confirmed fetal cardiac activity, miscarriage risk decreases as gestational age advances.
However, the current SooperTools calculator does not have a fetal-heartbeat input and does not claim to calculate a personalized post-heartbeat probability. This is an important limitation of the present tool and prevents the page from implying that heartbeat findings are incorporated into its numerical result.
ACOG also explains that ultrasound and, when appropriate, serum hCG testing may be used with medical history and examination to evaluate suspected early pregnancy loss.
How Should You Interpret the Result?
The most useful way to read the calculator is as a statistical reference, not as a prediction.
Example 1 — Age 30, Week 8
User situation: A person enters age 30 and pregnancy week 8 with no previous miscarriages selected.
Result: The calculator shows the age-based reference of about 9–17% and an earlier first-trimester week context.
Interpretation: These are population references. They do not establish the probability that this particular pregnancy will or will not continue.
Example 2 — Age 35, Week 10
User situation: A person enters age 35 and pregnancy week 10.
Result: The calculator shows the approximately 20% age reference and a later first-trimester pregnancy-week context.
Interpretation: The age reference comes from population data, while the pregnancy-week display communicates the general decline in risk with advancing gestation.
Example 3 — Age 40, Week 12
User situation: A person enters age 40 and pregnancy week 12.
Result: The calculator displays the approximately 40% age-based reference and a later first-trimester week context.
Interpretation: The result does not mean that this individual has a 40% personal chance of miscarriage. It is a population reference associated with age.
Why Can Two People Get Different Results?
Two pregnancies can have different statistical contexts because risk factors and clinical findings differ. Maternal age and previous pregnancy history can matter, while gestational age changes how risk is interpreted over time. Other clinically relevant information may include ultrasound findings, symptoms, laboratory results, and medical history.
An online calculator only works with the variables it actually models. Adding more checkboxes does not automatically make a medical estimate more accurate. That is why the current tool deliberately presents some inputs as context instead of applying unsupported numerical adjustments.
How Accurate Is a Miscarriage Calculator?
No online miscarriage calculator can guarantee an exact individual prediction. Accuracy depends on whether its underlying model has been validated for the population being assessed and whether the inputs correspond to the evidence used to build that model.
ACOG notes that diagnosing early pregnancy loss requires appropriate clinical evaluation. Symptoms such as bleeding and cramping can occur in both normal and abnormal pregnancies, and ultrasound or hCG testing may be needed to establish the diagnosis.
For this reason, the SooperTools calculator should be used for educational statistical context rather than diagnosis, reassurance, or clinical decision-making.
When Should You Contact a Healthcare Professional?
A calculator should not be used to determine whether a miscarriage is occurring. ACOG advises contacting an obstetrician-gynecologist for symptoms such as vaginal spotting or bleeding, especially when accompanied by pain, and explains that evaluation may include ultrasound and hCG testing.
Heavy bleeding, significant pain, passage of tissue, or other concerning symptoms warrant prompt medical attention rather than relying on an online risk estimate.
Common Questions
What is a miscarriage calculator?
It is an online tool that uses selected pregnancy information to provide statistical context about miscarriage risk. The result should not be treated as a personal diagnosis or guaranteed prediction.
What is the average miscarriage risk in known pregnancies?
ACOG states that early pregnancy loss occurs in about 10% of known pregnancies. Estimates vary depending on the population and how pregnancy loss is defined and measured.
Does miscarriage risk decrease each week?
In general, miscarriage risk decreases as pregnancy advances, although the exact pattern depends on the study population and clinical circumstances. A prospective study of asymptomatic women with confirmed fetal cardiac activity found a rapid decline through the early weeks studied.
Does age affect miscarriage risk?
Yes. ACOG identifies increasing maternal age as an important risk factor for early pregnancy loss, with substantially higher population-level frequencies reported at older ages.
Does a previous miscarriage increase the risk?
A prior early pregnancy loss is recognized as an important risk factor. The current SooperTools tool displays previous-loss history as context rather than applying an unsupported numerical multiplier.
Does a heartbeat guarantee that a miscarriage will not happen?
No. Fetal cardiac activity is an important clinical finding, but it does not make miscarriage impossible. Risk also depends on gestational age and other clinical factors.
Can a miscarriage calculator diagnose a miscarriage?
No. A diagnosis requires appropriate medical evaluation. ACOG explains that ultrasound, hCG testing, medical history, and examination may be used when early pregnancy loss is suspected.
Frequently Asked Questions
No. The current tool provides age-based statistical reference context and pregnancy-week context rather than a validated personalized probability.
Population-level miscarriage frequency increases with maternal age. ACOG reports approximately 20% at age 35, 40% at age 40, and 80% at age 45.
Miscarriage risk generally declines as gestational age advances. The exact estimate depends on the population studied and whether findings such as fetal cardiac activity were present.
The current interface records these selections as user context. It does not apply an unverified numerical adjustment, which avoids presenting an unsupported combined risk model as clinically validated.
No. The calculator is educational and does not diagnose pregnancy loss. Concerning symptoms or abnormal clinical findings require appropriate medical assessment.
Discuss your individual situation with your obstetrician-gynecologist or other qualified healthcare professional, especially if you have bleeding, pain, passage of tissue, or another concerning symptom.
Yes. The interactive tool lets you test valid pregnancy-week values and compare saved scenarios during the current page session.
Limitations of This Miscarriage Calculator
- The calculator provides population-level reference information rather than an individualized clinical prediction.
- The current implementation does not use a validated combined equation for all selected risk factors.
- Fetal heartbeat or ultrasound findings are not calculator inputs and are not incorporated into the displayed result.
- Research estimates can differ because studies use different populations, definitions, and measurement methods.
- A calculator cannot diagnose miscarriage or replace clinical assessment.
Related SooperTools
For broader information, continue with the SooperTools miscarriage risk guide. For related early-pregnancy topics, see early pregnancy symptoms, hCG levels, or use the due date calculator to review gestational dating. For conception-related calculations, use the pregnancy chances calculator.
References
- American College of Obstetricians and Gynecologists: Early Pregnancy Loss — general miscarriage frequency, maternal-age association, risk factors, symptoms, and diagnostic evaluation.
- Miscarriage risk for asymptomatic women after a normal first-trimester prenatal visit — prospective cohort evidence examining miscarriage risk by gestational age after confirmed fetal cardiac activity.
Written by: SooperTools Editorial Team
Page updated: September 27, 2026
This page explains the current SooperTools calculator behavior and the published medical evidence used for contextual information. The page update date does not imply that every underlying study was published or reviewed on that date.