Healthy weight gain, week by week.
Enter your pre-pregnancy weight, height and current week of pregnancy to see your recommended total weight gain based on the Institute of Medicine guidelines, how much you should have gained by now, and your target weekly rate for the rest of your pregnancy.
Your details
Your weight before becoming pregnant.
Feet portion of your height.
Inches portion of your height.
Your current week of pregnancy (1-42).
Your pre-pregnancy BMI decides your recommended gain range. The IOM guidelines assume about 1 to 4.5 lbs total in the first trimester, then a steady weekly rate in the second and third. Results update as you type.
What your numbers mean
Your recommended weight gain curve
Gain milestones for your pregnancy
IOM recommendations by BMI category
Institute of Medicine total weight gain guidelines by pre-pregnancy BMI. The highlighted row is your category. Twin pregnancies call for more gain; the underweight twin range has not been set due to insufficient data.
| Category | Pre-pregnancy BMI | Total gain (single baby) | Total gain (twins) |
|---|
Pregnancy weight gain, explained
Recommended Weight Gain During Pregnancy
The Institute of Medicine guidelines recommend weight gain based on pre-pregnancy BMI: underweight (BMI < 18.5) should gain 28-40 lbs, normal weight (18.5-24.9) should gain 25-35 lbs, overweight (25-29.9) should gain 15-25 lbs, and obese (BMI 30+) should gain 11-20 lbs. These ranges support healthy fetal development.
Weight Gain by Trimester
Most weight gain occurs in the second and third trimesters. During the first trimester, only 1-5 pounds is typical. In the second and third trimesters, normal-weight women should gain about 1 pound per week. The rate varies by pre-pregnancy BMI, overweight women should gain about 0.6 lbs/week and underweight women about 1.3 lbs/week.
Where Does the Weight Go?
At full term, pregnancy weight gain is distributed approximately as follows: baby (7-8 lbs), placenta (1.5 lbs), amniotic fluid (2 lbs), uterus growth (2 lbs), breast tissue (2 lbs), increased blood volume (4 lbs), body fluids (4 lbs), and maternal fat stores (5-9 lbs). Most of this weight is lost within 6 weeks postpartum.
Managing Weight During Pregnancy
Focus on nutrient-dense foods rather than "eating for two", you only need about 340 extra calories per day in the second trimester and 450 in the third. Regular moderate exercise (walking, swimming, prenatal yoga) is safe and beneficial for most pregnancies. Never attempt to lose weight during pregnancy without medical guidance.
Common questions
How much weight should I gain during pregnancy?
Total recommended gain depends on your pre-pregnancy BMI. Normal weight women (BMI 18.5-24.9) should gain 25-35 lbs. Underweight women should gain 28-40 lbs. Overweight women should gain 15-25 lbs. Obese women should gain 11-20 lbs. These ranges are based on IOM guidelines.
Is it okay to gain more than recommended?
Excessive weight gain during pregnancy increases the risk of gestational diabetes, preeclampsia, cesarean delivery, and postpartum weight retention. It can also increase the baby's risk of childhood obesity. However, do not restrict calories to prevent weight gain, focus on nutritious food choices.
What if I am not gaining enough weight?
Inadequate weight gain can lead to preterm birth and low birth weight. If you are struggling to gain weight, eat more calorie-dense nutritious foods like nuts, avocados, and whole-milk dairy. Consult your healthcare provider if nausea or food aversions are preventing adequate intake.
Will I lose the weight after delivery?
Most women lose about 10-13 lbs immediately after delivery (baby, placenta, amniotic fluid). Additional weight is lost over the following 6-12 months through breastfeeding (burns 300-500 extra calories daily), gradual return to normal activity, and natural reduction of body fluids. It typically takes 6-12 months to return to pre-pregnancy weight.
This calculator gives general guidance based on Institute of Medicine population guidelines, not a medical diagnosis or an individual prescription. The right weight gain for you depends on factors this tool cannot see, including twin pregnancy, pre-existing conditions, gestational diabetes and your baby's growth pattern. Never try to lose weight or restrict calories during pregnancy without medical supervision. Always follow the guidance of your obstetrician, midwife or prenatal care provider, and raise any concern about weight change, swelling or sudden gain with them promptly.