Pregnancy Weight Gain Calculator
Based on Institute of Medicine (IOM) guidelines. Individual guidance from your OB always wins.
How this works
Your BMI is calculated from height and pre-pregnancy weight using the standard formula (BMI = weight in lb × 703 ÷ height in inches²). The recommended total weight-gain range comes from the Institute of Medicine's 2009 report on Weight Gain During Pregnancy, which is what every Tennessee OB/GYN uses at intake.
A typical pattern for a normal-BMI singleton pregnancy: 1–4 lb in the first trimester, then ~1 lb per week through the second and third trimesters. Your OB plots this trajectory at each visit, not just the total number.
Limitations
Ranges assume a healthy pre-pregnancy baseline. Prior gestational diabetes, chronic hypertension, thyroid disorders, or bariatric surgery history can move your target up or down. Your OB — not this calculator — sets your individual target.
Sources: Institute of Medicine (2009), Weight Gain During Pregnancy: Reexamining the Guidelines.
Frequently asked questions
The Institute of Medicine (IOM) recommends 25–35 lb for normal-weight women (BMI 18.5–24.9), 28–40 lb for underweight, 15–25 lb for overweight, and 11–20 lb for those with a BMI of 30 or higher. Twin pregnancies add 10–20 lb to each range.
Weight gain accelerates in the second and third trimesters. A typical pattern: 1–4 lb in the first trimester, then about 1 lb per week through the rest of pregnancy for normal-BMI women. Your OB tracks the trajectory, not just the total.
Both under- and over-gain increase risks. Underweight women who under-gain risk low-birthweight babies; obese women who over-gain increase risks of gestational diabetes, preeclampsia, and C-section. Ranges are wider for underweight and narrower for higher-BMI to reflect this.
No. Tennessee OB/GYNs use IOM ranges as a starting point but tailor recommendations to individual health, prior pregnancy history, and lab work. If your OB gives you a different target, follow theirs.