Miscarriage Risk Calculator (Educational Estimate)
Use this tool to estimate statistical miscarriage risk from your current gestational week to 20 weeks. It is a rough screening estimate and not a diagnosis.
Important: this estimate cannot account for ultrasound findings (like fetal heartbeat), lab tests, or your complete medical history. Please discuss results with your OB/GYN or midwife.
Understanding miscarriage risk by week
Pregnancy loss risk is usually highest in the earliest weeks and tends to decline as pregnancy progresses. Many people search for a miscarriage probability calculator or chance of miscarriage by week because uncertainty can be emotionally difficult. A calculator can help with perspective, but it should always be viewed as a general guide rather than a prediction for one individual pregnancy.
| Gestational week | Typical average risk from that point forward* |
|---|---|
| 4–5 weeks | ~24–30% |
| 6 weeks | ~18% |
| 7 weeks | ~13% |
| 8 weeks | ~9% |
| 9 weeks | ~7% |
| 10 weeks | ~5–6% |
| 11–12 weeks | ~3–4% |
| 13–14 weeks | ~2–3% |
| 15+ weeks | ~2% or lower |
*These are broad population-level ranges and vary between studies, ultrasound findings, and clinical definitions.
How this miscarriage calculator works
The calculator starts with a baseline risk tied to gestational age, then adjusts based on factors commonly associated with increased miscarriage risk. Inputs include:
- Maternal age
- History of prior miscarriage(s)
- Current bleeding symptoms
- Nicotine exposure (smoking/vaping)
- Presence of chronic medical conditions linked to pregnancy complications
Because this is a simplified model, it does not include key clinical details such as fetal cardiac activity, quantitative hCG trends, progesterone, uterine anatomy, infection status, medication profile, or genetic testing data.
Risk categories used in results
- Low: under 5%
- Moderate: 5% to under 15%
- Elevated: 15% or higher
Major factors that can influence pregnancy loss risk
1) Maternal age
Age is one of the strongest predictors at the population level. Risk tends to rise from the mid-30s onward, largely due to chromosomal abnormalities becoming more common with age.
2) Prior miscarriage history
One prior miscarriage is common and does not automatically mean a high-risk future pregnancy. However, recurrent losses may justify additional evaluation with your clinician.
3) Bleeding in early pregnancy
Light spotting can occur in viable pregnancies, but moderate or heavy bleeding should prompt urgent medical review, especially if accompanied by cramping, severe pain, fever, dizziness, or shoulder pain.
4) Smoking and nicotine exposure
Smoking is associated with increased risk of miscarriage and other adverse pregnancy outcomes. Quitting at any point can improve maternal and fetal health.
5) Chronic medical conditions
Conditions such as uncontrolled thyroid disease, diabetes, antiphospholipid syndrome, lupus, and thrombophilias may raise risk if untreated. Preconception or early prenatal optimization can make a meaningful difference.
When to seek immediate care
Even if your calculator result looks low, symptoms always matter more than a statistical estimate.
What you can do next
- Schedule regular prenatal visits.
- Take prenatal vitamins with folic acid.
- Avoid smoking, alcohol, and non-prescribed substances.
- Review all medications and supplements with your clinician.
- Ask whether early ultrasound or bloodwork is appropriate for reassurance.
- Seek emotional support if anxiety is high—this is common and valid.
Frequently asked questions
Can a calculator tell me whether I will miscarry?
No. It estimates population risk, not certainty for an individual pregnancy.
Does seeing a heartbeat lower risk?
In many cases, yes—especially as gestation advances. Your provider can interpret this in context with your full clinical picture.
I had one miscarriage before. Is my risk always high now?
Not necessarily. A single prior miscarriage is common. Many people go on to have healthy pregnancies.
What if my result is elevated?
Use it as a prompt for earlier contact with your prenatal care team, not as a final verdict. Your care team may recommend monitoring and targeted evaluation.
Final note
If you came here searching for early pregnancy loss risk, miscarriage odds by age, or a first-trimester miscarriage risk calculator, remember: numbers can guide questions, but personalized care guides decisions. Bring your result to your OB/GYN, family doctor, or midwife so you can make a plan together.