Pink Mom MathPregnancy BMI Calculator
Calculate your pre-pregnancy Body Mass Index and see personalized IOM weight gain guidance.
What is Pre-Pregnancy BMI?
Body Mass Index (BMI) is calculated as weight in kilograms divided by height in metres squared. Pre-pregnancy BMI — your BMI before conception — is the figure used to determine your personalized gestational weight gain target.
The IOM 2009 guidelines classify women into four BMI categories at conception, each with a specific total weight gain range:
- Underweight (BMI < 18.5): 12.5–18 kg
- Normal weight (BMI 18.5–24.9): 11.5–16 kg
- Overweight (BMI 25–29.9): 7–11.5 kg
- Obese (BMI ≥ 30): 5–9 kg
After calculating your BMI, use the pregnancy weight gain calculator to see a week-by-week trajectory chart with your personalized IOM corridor.
Frequently Asked Questions
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Related Guides
Healthy Weight Gain During Pregnancy: IOM Guidelines Explained
IOM weight gain recommendations by pre-pregnancy BMI category, why staying in range matters, and practical guidance for singleton and twin pregnancies.
Gestational Diabetes: Risk Factors and Screening
Risk factors for gestational diabetes, when and how screening happens, what the glucose challenge test involves, and how GDM is managed during pregnancy.
This calculator provides estimates for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your healthcare provider with questions about your health or your baby's health.
BMI categories per WHO/CDC classification. IOM 2009 gestational weight gain recommendations.