Calculator
Example Data Table
| Age | BMI | Gestation | Key Factors | Score | Category |
|---|---|---|---|---|---|
| 24 | 22.0 | 18 weeks | No major history flags | 0 | Lower Risk |
| 31 | 28.4 | 25 weeks | Family history, inactivity | 4 | Lower Risk |
| 36 | 32.1 | 20 weeks | PCOS, family history | 8 | Elevated Risk |
| 38 | 35.8 | 12 weeks | Prior GDM, prediabetes, prior large baby | 15 | Very High Risk |
These are example scenarios for orientation only. Actual diagnosis requires prenatal blood testing.
Formula Used
This calculator uses a custom weighted screening score. It is designed for education and visit planning, not diagnosis.
Total Score = Age Points + BMI Points + Prior GDM + Prediabetes + Family History + Prior Large Baby + PCOS + Hypertension + Inactivity
Age Points
Under 25 = 0
25 to 34 = 1
35 to 39 = 2
40 or older = 3
BMI Points
Under 25 = 0
25.0 to 29.9 = 1
30.0 to 34.9 = 2
35.0 or higher = 3
Binary Risk Points
Prior gestational diabetes = 4
Prediabetes before pregnancy = 4
Family history of type 2 diabetes = 2
Previous baby over 4 kg / 9 lb = 2
PCOS = 2
Hypertension history = 1
Low physical activity = 1
Custom Risk Index = (Total Score ÷ 22) × 100
Category Bands
0 to 4 = Lower Risk
5 to 8 = Elevated Risk
9 to 13 = High Risk
14 to 22 = Very High Risk
How to Use This Calculator
- Enter maternal age, gestational weeks, and pre-pregnancy BMI.
- Select Yes or No for each medical or history factor.
- Choose the number of decimals you want displayed.
- Press Calculate Risk to display the result above the form.
- Review the weighted score, custom index, category, and guidance note.
- Study the bar chart to see which factors contribute most.
- Use the breakdown table for visit preparation or counseling notes.
- Export the result block through CSV or PDF if needed.
- Discuss any elevated result with your prenatal clinician promptly.
Frequently Asked Questions
1. Does this calculator diagnose gestational diabetes?
No. It estimates an educational risk score from common screening factors. Diagnosis requires blood testing ordered by a prenatal clinician.
2. When is gestational diabetes usually screened?
Routine screening is commonly performed during the middle of pregnancy, often around 24 to 28 weeks. Higher-risk pregnancies may be tested earlier.
3. Why does prior gestational diabetes add more points?
A past pregnancy affected by gestational diabetes is one of the strongest repeat risk markers, so this calculator weights it more heavily.
4. Why is pre-pregnancy BMI included?
Higher BMI is associated with greater insulin resistance, so it can raise gestational diabetes risk. This tool uses BMI as a weighted screening input.
5. What does the custom risk index mean?
It shows how much of the calculator’s maximum weighted score is present. It is a planning index, not a medical probability.
6. Can a low score guarantee safety?
No. A low score does not rule out gestational diabetes. Keep scheduled prenatal visits and routine screening even if your score seems low.
7. Why are family history and PCOS included?
Both can reflect underlying insulin-resistance patterns or metabolic vulnerability, so they are commonly considered when discussing gestational diabetes risk.
8. Should I seek medical advice if my category is high?
Yes. Bring the result to your prenatal clinician, especially if you are in the high or very high range or have not had glucose screening yet.