How much weight should I gain during pregnancy?

IOM guidelines recommend: Underweight (BMI <18.5): 28–40 lbs | Normal weight (18.5–24.9): 25–35 lbs | Overweight (25–29.9): 15–25 lbs | Obese (BMI ≥30): 11–20 lbs. Twin pregnancies have higher targets.

How much weight is normal in each trimester?

Most guidelines recommend 1–4.4 lbs in the first trimester, followed by about 1 lb per week in the second trimester, and slightly less in the third. Total gain depends on pre-pregnancy BMI.

What happens if I gain too much weight during pregnancy?

Excessive gestational weight gain is linked to higher risk of gestational diabetes (GDM), larger babies (macrosomia), C-section delivery, and difficulty losing weight postpartum. It is not harmful in small excess but worth managing.

Does weight gain during pregnancy affect the baby?

Yes. Both too little and too much gestational weight gain can affect baby's birthweight and health. Adequate gain supports the baby's development; excessive gain increases risks for both mother and baby.

Pregnancy Weight Gain Calculator

Q: How much weight is normal in each trimester?

Most guidelines recommend 1–4.4 lbs in the first trimester, followed by about 1 lb per week in the second trimester, and slightly less in the third. Total gain depends on pre-pregnancy BMI.

Q: What happens if I gain too much weight during pregnancy?

Excessive gestational weight gain is linked to higher risk of gestational diabetes (GDM), larger babies (macrosomia), C-section delivery, and difficulty losing weight postpartum. It is not harmful in small excess but worth managing.

Q: Does weight gain during pregnancy affect the baby?

Yes. Both too little and too much gestational weight gain can affect baby's birthweight and health. Adequate gain supports the baby's development; excessive gain increases risks for both mother and baby.

Calculate recommended pregnancy weight gain based on pre-pregnancy BMI using IOM/ACOG guidelines. Track your progress and see trimester-by-trimester targets.

Pre-Pregnancy Weight

lbs

Height (feet)

Height (inches)

Weeks Pregnant

weeks

Current Weight

lbs

Pre-Pregnancy BMI

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BMI Category —

Recommended Total Gain (IOM) —

Weight Gained So Far —

Gain Status —

Extended More scenarios, charts & detailed breakdown ▾

Pre-Pregnancy Weight

lbs

Height (feet)

Height (inches)

Weeks Pregnant

weeks

Current Weight

lbs

Pre-Pregnancy BMI

—

Weight Gained —

Recommended Gain by Now —

Remaining Recommended Gain —

Progress Status —

Professional Full parameters & maximum detail ▾

Pre-Pregnancy Weight

lbs

Height (feet)

Height (inches)

Weeks Pregnant

weeks

Current Weight

lbs

Pregnancy Type

Gestational Diabetes Risk Factor

BMI & Guidelines

Pre-Pregnancy BMI —

BMI Category —

Recommended Total Gain —

Weekly Gain Target (2nd/3rd tri) —

Current Progress

Weight Gained So Far —

Gain Status —

Additional Calories Recommended —

Weight Distribution

Baby/Placenta/Fluid (est.) —

Maternal Stores (est.) —

Clinical Flags

GDM Risk Flag —

Postpartum Retention Estimate —

How to Use This Calculator

Enter your pre-pregnancy weight, height (feet and inches), current weeks pregnant, and current weight.
The calculator determines your pre-pregnancy BMI and recommended total weight gain range using IOM guidelines.
Use the "Twins" tab for twin pregnancy guidelines.
Use the "Trimester Breakdown" tab to see week-by-week rate targets.

Formula

Pre-pregnancy BMI = weight(kg) / height(m)²

IOM recommended gain — Underweight: 28–40 lbs | Normal: 25–35 lbs | Overweight: 15–25 lbs | Obese: 11–20 lbs
2nd/3rd trimester rate: 0.4–1.3 lbs/week depending on BMI category

Example

Example: A woman 5'5", 140 lbs pre-pregnancy (BMI 23.3 — normal weight), currently 20 weeks at 148 lbs: gained 8 lbs. Recommended by 20 weeks: ~12.5 lbs. Status: slightly below pace — monitor and ensure adequate nutrition.

Frequently Asked Questions

IOM guidelines recommend: Underweight (BMI <18.5): 28–40 lbs | Normal weight (18.5–24.9): 25–35 lbs | Overweight (25–29.9): 15–25 lbs | Obese (BMI ≥30): 11–20 lbs. Twin pregnancies have higher targets.
Most guidelines recommend 1–4.4 lbs in the first trimester, followed by about 1 lb per week in the second trimester, and slightly less in the third. Total gain depends on pre-pregnancy BMI.
Excessive gestational weight gain is linked to higher risk of gestational diabetes (GDM), larger babies (macrosomia), C-section delivery, and difficulty losing weight postpartum. It is not harmful in small excess but worth managing.
Yes. Both too little and too much gestational weight gain can affect baby's birthweight and health. Adequate gain supports the baby's development; excessive gain increases risks for both mother and baby.

Related Calculators

Sources & References (5) ▾

IOM (National Academies) — Weight Gain During Pregnancy: Reexamining the Guidelines (2009) — National Academies Press / IOM
ACOG — Practice Bulletin No. 230: Obesity in Pregnancy (2021) — ACOG
Goldstein RF et al. — Association of Gestational Weight Gain With Maternal and Infant Outcomes. JAMA. 2017;317(21):2207-2225 — JAMA
CDC — Gestational Weight Gain — CDC
WHO — Gestational weight gain recommendations — World Health Organization