Pregnancy Weight Gain Calculator

Your recommended weight gain depends on your pre-pregnancy BMI. Underweight women (BMI < 18.5) should gain 28–40 lb; healthy weight women (BMI 18.5–24.9) should gain 25–35 lb; overweight women (BMI 25–29.9) should gain 15–25 lb; and obese women (BMI ≥ 30) should gain 11–20 lb. If you're carrying twins, the ranges are higher across all categories. See also our calculate Breast Cancer Recurrence Risk Estimated 5-Year Recurrence Risk.

Guidelines from the Institute of Medicine (IOM) base recommended pregnancy weight gain on your pre-pregnancy BMI. Your BMI is calculated from your height and weight before pregnancy, which then places you in an underweight, healthy weight, overweight, or obese category — each with its own target range.

During the first trimester (weeks 1–13), most guidelines recommend gaining only 1–4 pounds total, regardless of BMI category. The bulk of pregnancy weight gain happens in the second and third trimesters, where a steady weekly rate is expected.

For healthy-weight women carrying a single baby, roughly 1 pound per week in the second and third trimesters is typical. Underweight women may aim for slightly more (1.0–1.3 lb/week), while overweight women should target less (0.5–0.7 lb/week) and obese women even less (0.4–0.6 lb/week). You might also find our Conception Calculator useful.

To gain about 1 pound per week, consuming approximately 300 extra calories per day above your normal needs is generally sufficient. Focus on nutrient-dense foods like lean proteins, whole grains, dairy, fruits, and vegetables rather than simply eating more of anything.

Twin pregnancies require greater weight gain. IOM recommendations for twins are: healthy weight women 37–54 lb, overweight women 31–50 lb, and obese women 25–42 lb. Underweight guidelines for twins are less established, so consult your healthcare provider directly.

Yes — gaining too much weight increases the risk of gestational diabetes, high blood pressure, cesarean delivery, and postpartum weight retention. Gaining too little can lead to preterm birth, low birth weight, and developmental issues. Staying within your recommended range helps reduce risks for both you and your baby.

No — intentional weight loss during pregnancy is not recommended, even for women who are overweight or obese. Instead, focus on gaining the minimum recommended amount within your BMI category. Always discuss your personal goals and any concerns with your doctor or midwife.