Prenatal nutrition
Pregnancy BMI & Weight Gain Guide
Pre-pregnancy BMI determines recommended weight gain ranges. Enter your data to see trimester-adjusted targets and personalized guidance. Always review results with your obstetric provider.
Pre-pregnancy BMI
22.8
Normal pre-pregnancy BMIAim for 11.5–16 kg total gain, with 0.4–0.5 kg/week in the 2nd and 3rd trimesters.
Current gain
6.0 kg (6.0 kg)
Weight gain is within the guideline range. Continue balanced meals, hydration, and prenatal care.
Guideline summary
- Total recommended gain: 11.5 – 16 kg (11.5 – 16.0 kg)
- Weekly gain (2nd/3rd trimester): 0.4 – 0.5 kg/week
- Expected gain by 24.0 weeks: 5.6 – 6.7 kg (5.6 – 6.7 kg)
How to Use This Calculator
Enter baseline data
Provide pre-pregnancy weight, height, and current gestational age. Accuracy improves if height is measured and weight is recorded on a calibrated scale.
Compare gain with guidelines
Use trimester-adjusted expectations to see whether your current gain aligns with Institute of Medicine (IOM) recommendations.
Discuss changes with your provider
Bring results to prenatal appointments to tailor nutrition, activity, and metabolic monitoring plans.
Formula
BMI = Weight (kg) ÷ [Height (m)]²
Weight gain = Current weight − Pre-pregnancy weight
Expected gain by week = First-trimester basal gain (~1–2 kg) + Weekly gain × (weeks − 13)
Guideline values derived from IOM 2009 recommendations for singleton pregnancies.
Full Description
Balanced weight gain supports fetal growth, placenta development, and maternal reserves. Too little gain increases risk of small-for-gestational-age infants, while excessive gain raises chances of gestational diabetes, hypertensive disorders, and postpartum retention. BMI-based guidelines personalize targets but should be nuanced by body composition, metabolic factors, and clinical history.
Collaborate with registered dietitians, obstetricians, and physical therapists to craft meal plans, activity routines, and metabolic monitoring tailored to your needs. This calculator complements, but does not replace, individualized medical advice.
Frequently Asked Questions
How accurate are BMI-based recommendations?
BMI does not distinguish muscle from fat. Use it as a starting point—providers adjust goals based on individual health status.
What if I have nausea or hyperemesis?
Contact your provider. Intravenous fluids, antiemetics, and specialized nutrition may be required to prevent excessive weight loss.
Do twins have different targets?
Yes—twin pregnancies require higher gains. Use a twin-specific calculator and consult MFM specialists.
Can I lose weight intentionally during pregnancy?
Intentional weight loss is generally not recommended without medical supervision. Focus on nutrient quality, moderate activity, and overall wellness.