Week 20: 7.3–12.3 lb recommended so far. Add your current weight to compare.
Find the recommended total weight gain for your pregnancy based on your pre-pregnancy BMI, using the Institute of Medicine guidelines, and see whether your gain so far is on track for your current week.
Pre-pregnancy BMI → IOM total-gain range (e.g. 25–35 lb for normal weight)
How much weight to gain in pregnancy depends mainly on where you started. The calculator first computes your pre-pregnancy body mass index (BMI) from your pre-pregnancy weight and height, then looks up the recommended total weight-gain range for that BMI category from the 2009 Institute of Medicine (IOM) guidelines, which the CDC publishes for the public. A person who began at a normal weight is advised to gain 25–35 pounds; someone underweight, 28–40; someone overweight, 15–25; and someone with obesity, 11–20. The calculator also plots a week-by-week target: gain is small in the first trimester (about 1–4.5 pounds total), then climbs at a steady rate through the second and third trimesters, ending at the recommended total around 40 weeks. If you enter your current weight and week of pregnancy, it compares your actual gain against the recommended range for that week and tells you whether you are below, within, or above it. For the normal, overweight, and obese categories, twin pregnancies use separate, higher provisional IOM ranges. These are population-based guidelines for healthy pregnancies — your own target may differ, and your prenatal provider tracks your gain in context, so their guidance always comes first.
Someone who weighed 60 kg at 165 cm before pregnancy is now 20 weeks along. What weight gain is recommended?
The single biggest factor in how much weight to gain is pre-pregnancy BMI: lower starting BMI means a higher recommended gain, and higher starting BMI means a lower one. The Institute of Medicine ranges — 28–40, 25–35, 15–25, and 11–20 pounds for the underweight, normal, overweight, and obese categories — are for a single baby in a healthy pregnancy. Gain is not meant to be even across pregnancy: the first trimester adds little (around 1–4.5 pounds), and most gain happens in the second and third trimesters at a fairly steady weekly rate. Gaining within the recommended range is associated with better outcomes for both parent and baby; gaining well above it raises the risk of a large-for-gestational-age baby, cesarean delivery, and weight retention after birth, while gaining well below it raises the risk of a small baby and preterm birth. Twin pregnancies need more (the IOM gives provisional ranges of roughly 37–54 pounds for normal-weight, 31–50 for overweight, and 25–42 for obese), and there is no firm guideline for underweight twin pregnancies. The number on the scale is only part of the picture — nutrient quality, blood pressure, and how your baby is growing all matter, which is why prenatal visits track more than weight alone.
It depends on your pre-pregnancy BMI. The Institute of Medicine recommends a total gain of 28–40 pounds if you were underweight, 25–35 pounds if you were a normal weight, 15–25 pounds if you were overweight, and 11–20 pounds if you had obesity, for a single baby. The calculator looks up your category from your pre-pregnancy weight and height and shows the matching range.
Gain is small in the first trimester (about 1–4.5 pounds total) and then proceeds at a steady rate through the second and third trimesters, ending at the recommended total around week 40. The calculator models that path and shows the recommended range for your current week, so you can see whether your gain so far is on track.
If your gain is outside the recommended range for your week, talk to your prenatal provider rather than making sudden changes on your own. Gaining well above the range raises the risk of a large baby, cesarean birth, and postpartum weight retention; gaining well below it raises the risk of a small baby and preterm birth. Your provider can help you adjust safely — pregnancy is not a time for weight-loss dieting without medical guidance.
Twin pregnancies need more weight gain. The Institute of Medicine gives provisional ranges of about 37–54 pounds for a normal-weight pregnancy, 31–50 pounds for overweight, and 25–42 pounds for obese. There is no firmly established guideline for underweight twin pregnancies. Switch the calculator to the twin setting and follow your provider's individualized target.
Before pregnancy. The recommended gain is based on your pre-pregnancy BMI — your weight and height at the start of pregnancy. Using your current pregnant weight would put you in the wrong category and give the wrong target.
Yes. Day-to-day and week-to-week weight shifts with fluid, food, and the time of day, so a single reading is not very meaningful. What matters is the overall trend across weeks relative to the recommended range. If the trend is consistently outside the range, raise it at your next prenatal visit.
Reference:
Institute of Medicine (IOM). Weight Gain During Pregnancy: Reexamining the Guidelines. Washington, DC: National Academies Press; 2009. Recommended ranges by pre-pregnancy BMI (consumer summary): Centers for Disease Control and Prevention, Weight Gain During Pregnancy. https://www.cdc.gov/maternal-infant-health/pregnancy-weight/index.html