Pregnancy Weight Gain Calculator

Find out how much weight you should gain during pregnancy based on your pre-pregnancy BMI. Includes trimester breakdown and week-by-week schedule using IOM 2009 guidelines.

Your details IOM 2009 guidelines
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Enter 1–42, or leave blank for full guide
FAQs
How much weight should I gain during pregnancy? ›
Per the 2009 Institute of Medicine (IOM) guidelines: Underweight (BMI <18.5): gain 28–40 lbs; Normal weight (BMI 18.5–24.9): gain 25–35 lbs; Overweight (BMI 25–29.9): gain 15–25 lbs; Obese (BMI ≥30): gain 11–20 lbs. For twins: Normal weight 37–54 lbs; Overweight 31–50 lbs; Obese 25–42 lbs. Weight gained during pregnancy includes the baby (~7–8 lbs), placenta (~1.5 lbs), amniotic fluid (~2 lbs), uterus growth (~2 lbs), breast tissue (~2 lbs), blood (~4 lbs), and fluid/fat stores (~7–12 lbs).
How much weight should I gain per week during pregnancy? ›
First trimester (weeks 1–13): Very little weight gain expected — typically 1–4.5 lbs total. Some women lose weight due to nausea. Second trimester (weeks 14–27): Gain begins in earnest — about 1 lb/week for normal-weight women. Third trimester (weeks 28–40): Continued gain of about 1 lb/week. Overweight and obese women should gain at a slower rate (0.5–0.7 lbs/week in the 2nd/3rd trimester). Underweight women should gain at a faster rate (~1.2 lbs/week).
What if I'm gaining too much or too little weight? ›
Gaining too much weight increases risks of gestational diabetes, preeclampsia, C-section, and having a large baby. It also makes it harder to lose weight postpartum. Gaining too little increases risks of preterm birth, low birth weight, and developmental delays. If you're outside the recommended range, don't try to lose weight or drastically change your diet without guidance. Talk to your OB or midwife — they'll account for your full health picture including any complications.