Pregnancy Weight Tracker

What Is a Pregnancy Weight Tracker?

Track healthy pregnancy weight gain by week and trimester. Get personalized IOM-recommended ranges based on your pre-pregnancy BMI with a visual weight gain curve. This calculator runs entirely in your browser — your data stays private, and no account is required.

Pregnancy Weight Gain Guidelines

Weight gain during pregnancy is a critical marker of maternal and fetal health. The Institute of Medicine (IOM) — now the National Academy of Medicine — published evidence-based guidelines that recommend different total weight gain ranges based on pre-pregnancy BMI. These guidelines balance the needs of the developing baby with the health of the mother, reducing risks of complications like gestational diabetes, preeclampsia, and delivery difficulties. This tracker uses those IOM guidelines to show your personalized healthy range and compare your current progress week by week. Calculate your starting BMI with our BMI Calculator.

Weight Gain by Trimester

First trimester (weeks 1–13): Most women gain just 1–5 pounds total. Some lose weight due to morning sickness, which is usually normal. The baby is tiny at this stage — most of the early gain is increased blood volume and fluid. Second trimester (weeks 14–27): This is when weight gain accelerates. Normal-weight women should gain about 1 pound per week. The baby grows rapidly, and the placenta, amniotic fluid, and maternal blood volume all increase substantially. Third trimester (weeks 28–40): Gain continues at roughly 1 pound per week, though it may slow in the final weeks. The baby accounts for most of the weight increase during this phase, going from about 2 pounds to 6–9 pounds at birth. Track your nutritional intake alongside weight gain with our Calorie Calculator.

Where Does the Weight Go?

For a total gain of 30 pounds in a normal-weight pregnancy: the baby accounts for 7–8 lbs, placenta 1.5 lbs, amniotic fluid 2 lbs, uterine growth 2 lbs, breast tissue increase 2 lbs, increased blood volume 4 lbs, extra body fluid 4 lbs, and maternal fat stores 7–8 lbs. The fat stores are not just cosmetic — they provide essential energy reserves for labor, delivery, and breastfeeding. Most women lose 10–13 lbs immediately at delivery (baby + placenta + amniotic fluid), with the remaining weight gradually decreasing over the following 6–12 months. Monitor your daily nutrition with our Macro Calculator.

Where Pregnancy Weight Goes

Understanding Healthy Weight Gain During Pregnancy

Weight gain during pregnancy supports fetal development, placental growth, increased blood volume, amniotic fluid, breast tissue development, and fat stores needed for breastfeeding. The Institute of Medicine (IOM) guidelines recommend total weight gain based on pre-pregnancy BMI: 28–40 pounds for underweight women (BMI below 18.5), 25–35 pounds for normal weight (BMI 18.5–24.9), 15–25 pounds for overweight (BMI 25–29.9), and 11–20 pounds for obese women (BMI 30+). Twin pregnancies require higher gains: 37–54 pounds for normal weight, 31–50 for overweight, and 25–42 for obese women. These ranges are guidelines, not rigid rules — your healthcare provider will adjust based on your specific health profile.

Where Pregnancy Weight Goes

Weight Gain by Trimester

Weight gain is not linear throughout pregnancy. During the first trimester (weeks 1–13), most women gain only 1–5 pounds total — some may even lose weight due to morning sickness. The second trimester (weeks 14–27) sees the most consistent gain, typically about 1 pound per week. The third trimester (weeks 28–40) continues at approximately 1 pound per week, though some women experience a plateau or slight slowdown near the end. Rapid weight gain (more than 2 pounds in a week) or sudden gain accompanied by swelling can indicate preeclampsia and should be reported to your healthcare provider immediately. Track your pregnancy timeline with our Due Date Calculator.

Nutrition Quality Over Quantity

The old advice to "eat for two" is misleading — you need only about 340 extra calories per day in the second trimester and 450 extra in the third (roughly the equivalent of a hearty snack, not a full extra meal). What matters more than total calories is nutritional quality: adequate protein (75–100g daily) for fetal tissue development, iron (27mg daily) for expanded blood volume, calcium (1,000mg daily) for bone development, folate (600mcg daily) for neural tube protection, and DHA omega-3 (200–300mg daily) for brain development. Deficiencies in these nutrients can affect fetal development regardless of total weight gain. Monitor your nutrient intake with our Macro Calculator and Protein Calculator.

Managing Weight Gain Concerns

Gaining too little or too much both carry risks. Insufficient gain is associated with preterm birth, low birth weight, and developmental delays. Excessive gain increases risks of gestational diabetes, preeclampsia, cesarean delivery, and postpartum weight retention. If your gain is tracking outside the recommended range, discuss adjustments with your prenatal care provider before making dietary changes. Light to moderate exercise (walking, swimming, prenatal yoga) is recommended for most pregnant women and can help manage weight gain while reducing back pain, improving sleep, and preparing for labor. Never undertake restrictive dieting during pregnancy without medical supervision.

Postpartum Weight Loss Expectations

Immediately after delivery, most women lose approximately 10–13 pounds (baby, placenta, amniotic fluid). Additional fluid retention resolves over the following weeks. Most women retain 5–15 pounds above pre-pregnancy weight at 6 weeks postpartum. Breastfeeding burns approximately 300–500 extra calories daily, which can accelerate weight loss for some women, though others find that breastfeeding increases appetite proportionally. Research suggests that most women return to within 2–5 pounds of their pre-pregnancy weight by 12 months postpartum with moderate exercise and balanced nutrition. Rapid weight loss during breastfeeding is not recommended, as caloric restriction can affect milk supply and quality. Calculate your baseline metabolic needs with our BMR Calculator and TDEE Calculator.

Special Considerations for Multiple Pregnancies

Twin pregnancies require significantly more weight gain — the IOM recommends 37–54 pounds for normal-weight women carrying twins, compared to 25–35 for singletons. Triplet and higher-order pregnancies have even higher targets, though specific guidelines are less well-established due to smaller study populations. The additional weight supports the development of multiple placentas, increased amniotic fluid, and the higher caloric demands of growing multiple fetuses simultaneously. Women carrying multiples typically need an additional 300 calories per day per fetus above singleton recommendations, totaling approximately 600–900 extra daily calories for twins. Work closely with your OB or maternal-fetal medicine specialist to monitor weight gain in multiple pregnancies.

Pre-Existing Health Conditions and Weight Monitoring

Women with gestational diabetes, preeclampsia risk factors, thyroid disorders, or eating disorder history require more careful weight monitoring during pregnancy. Gestational diabetes management may paradoxically lead to less weight gain (due to carbohydrate restriction) while still supporting healthy fetal growth. Women with a history of eating disorders should work with both an obstetrician and a mental health professional experienced in perinatal care, as pregnancy can trigger or exacerbate disordered eating patterns. For all pregnant women, the focus should be on healthy, consistent weight gain within recommended ranges rather than specific numbers on the scale. Track related health metrics with our BMI Calculator and Pregnancy Calculator.

Remember that every pregnancy is unique, and individual weight gain patterns vary widely even within recommended ranges. Weekly fluctuations of 1–2 pounds are normal and can be caused by water retention, bowel movements, and time of day. Focus on the overall trend rather than any single weigh-in.

How to Use This Calculator

1. Enter pre-pregnancy weight and height — Your starting BMI determines the recommended total gain range per IOM guidelines.
2. Enter weekly weight measurements — Log weight each week. The tracker plots actual gain against the recommended curve.
3. Review the trend — Shows whether you're within, above, or below the recommended range with weekly tracking.
4. Share with your provider — Generates a printable summary for prenatal appointments to discuss with your healthcare team.

Tips and Best Practices

See also: BMI Calculator · Calorie Calculator · Macro Calculator · Due Date Calculator · Baby Cost Calculator