Pregnancy Weight Gain Calculator
Important Health Disclaimer
This calculator provides general guidelines based on IOM recommendations. Every pregnancy is unique. Always consult your healthcare provider for personalized advice on weight gain during pregnancy. Do not make dietary or exercise changes based solely on this tool.
Weeks 1-42
Pre-Pregnancy BMI
0
--
Recommended Total Weight Gain
-- lbs
Recommended Gain by Week 20
-- lbs
Recommended Weekly Gain (2nd & 3rd Trimester)
-- lbs/week
Weight Gain Trajectory
Understanding Pregnancy Weight Gain
Gaining an appropriate amount of weight during pregnancy supports your baby's growth and development while reducing risks for both mother and child. The Institute of Medicine (IOM) published evidence-based guidelines that recommend different weight gain ranges depending on a woman's pre-pregnancy Body Mass Index. These guidelines have been widely adopted by obstetricians and midwives in the United States and many other countries.
For a singleton pregnancy, the IOM recommends that underweight women (BMI below 18.5) gain 28 to 40 pounds, normal-weight women (BMI 18.5 to 24.9) gain 25 to 35 pounds, overweight women (BMI 25 to 29.9) gain 15 to 25 pounds, and obese women (BMI 30 or above) gain 11 to 20 pounds. Twin pregnancies call for higher totals: 37 to 54 pounds for normal-weight women, 31 to 50 for overweight women, and 25 to 42 for obese women. Most weight gain occurs during the second and third trimesters, with only about 1 to 5 pounds gained in the first trimester.
Weight gain during pregnancy comes from the baby, placenta, amniotic fluid, increased blood volume, uterine growth, breast tissue, and maternal fat stores that fuel breastfeeding. Gaining too little increases the risk of preterm birth and low birth weight, while gaining too much raises the likelihood of gestational diabetes, preeclampsia, cesarean delivery, and difficulty losing weight postpartum. This calculator plots a week-by-week trajectory based on IOM guidelines, but remember that individual needs vary. Your healthcare provider can offer personalized guidance based on your medical history and the specifics of your pregnancy.