Calculator Inputs
Enter clinical and history information. Blank optional fields are ignored by the scoring model.
Example Data Table
These example rows are illustrative only and show how multiple factors can shift the weighted score.
| Profile | Gestational Weeks | Major Factors | Example Risk Band |
|---|---|---|---|
| Case A | 31.2 | Prior preterm birth, cervical length 22 mm, mild contractions | High |
| Case B | 28.5 | Twins, smoking, positive fibronectin, pelvic pressure | Very High |
| Case C | 24.0 | No prior preterm birth, cervical length 34 mm, negative fibronectin | Low |
| Case D | 33.4 | Bleeding, regular contractions, fluid leakage | Very High |
Formula Used
This calculator uses an educational weighted score, not a validated diagnostic equation. Each clinical factor adds or subtracts points based on relative concern.
Risk Score = Sum of all assigned factor weights
Estimated Risk (%) = 100 / (1 + e-((Score - 7.5) / 3.5))
Higher-risk findings include prior preterm birth, multifetal pregnancy, short cervix, positive fetal fibronectin, bleeding, regular contractions, and possible fluid leakage. Reassuring findings such as longer cervical length or negative fibronectin reduce the score modestly.
Important: This model supports awareness and discussion. It should never replace obstetric assessment, monitoring, imaging, or emergency evaluation.
How to Use This Calculator
- Enter maternal age, gestational weeks, and BMI.
- Add historical factors such as previous preterm births or cervical procedures.
- Include current pregnancy findings like cervical length or fibronectin result if available.
- Record symptom-related information, including contractions, bleeding, pelvic pressure, or fluid leakage.
- Submit the form to view the estimated percentage, score, risk band, and factor breakdown.
- Use CSV or PDF export to save results for discussion or documentation.
- Seek urgent care for concerning symptoms, regardless of the calculator output.
FAQs
1. Is this calculator a medical diagnosis?
No. It is an educational screening aid that summarizes risk features. Diagnosis and treatment decisions require direct assessment by a qualified maternity clinician.
2. Can I use it without cervical length data?
Yes. Optional fields can stay blank. The model will calculate a score from the information you do enter, but the estimate may be less informative.
3. Why does a negative fibronectin result lower the score?
In selected clinical settings, a negative result can be reassuring. This calculator reflects that with a modest score reduction, not a guarantee of safety.
4. Should I rely on the percentage alone?
No. Symptoms matter. Bleeding, regular contractions, or fluid leakage deserve prompt clinical review even if the percentage does not look extreme.
5. Does this work for twins?
Yes. Multifetal pregnancy is included as a major risk factor because twin and higher-order pregnancies generally have a higher baseline chance of preterm delivery.
6. Why are some factors protective?
A longer cervix, a negative fibronectin test, and strong prenatal follow-up can make the overall picture more reassuring, so the weighted score decreases slightly.
7. Can this replace hospital monitoring?
No. It cannot replace fetal monitoring, cervical assessment, ultrasound, swab testing, or clinician judgment. It is only a structured interpretation tool.
8. When should urgent help be sought?
Seek urgent maternity care for fluid leakage, bleeding, painful regular contractions, fever, severe pain, reduced fetal movement, or any sudden worsening symptom.