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Pregnancy Weight Gain Calculator

Look up cited IOM and ACOG pregnancy weight-gain ranges from prepregnancy BMI, including explicit singleton, twin and missing-evidence boundaries.

Use this result well

Inputs that matter
Prepregnancy height and weight plus singleton or twin pregnancy type
Output to expect
Prepregnancy BMI category and the matching cited total range; singleton rows also show the complete second/third-trimester interval and first-trimester assumption
How it works
Calculates BMI, selects the cited IOM/ACOG row and returns an explicit no-established-range state for underweight twins instead of extrapolating
  • Treat population ranges as discussion context, not a personal target or fetal-growth assessment; prenatal care may recommend a different plan.
  • The cited twin table has no underweight range or weekly-rate table. Do not borrow another category or apply singleton weekly rates.

Choose your path

Built around the job you need to finish

Look up cited IOM/ACOG pregnancy weight-gain ranges from prepregnancy BMI while preserving singleton weekly intervals and the missing underweight-twin evidence boundary.

Singleton pregnancy reviewing a cited range

See the complete total and second/third-trimester intervals.

Enter prepregnancy height/weight and choose Singleton.

Sees a range and first-trimester assumption, not a point target.

Twin pregnancy with normal, overweight or obese BMI

Use the cited twin total table without a fabricated weekly rate.

Choose Twins and inspect the matching total range and weekly-table limitation.

Does not reuse singleton weekly rates for twins.

Underweight adult with twins or a clinically complex pregnancy

Recognize when the cited table has no answer.

Receive an explicit no-established-range result and take it to the prenatal team.

Does not borrow another BMI row or self-prescribe gain.

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Reference & details

How it works

Prepregnancy BMI row

BMI uses measurements from before pregnancy and selects the underweight, normal, overweight or obese row used by the cited guidance.

BMI = prepregnancy weight (kg) ÷ height² (m²)

Singleton total and weekly intervals

The cited singleton totals are 28–40, 25–35, 15–25 and 11–20 lb. Second/third-trimester intervals are 1.0–1.3, 0.8–1.0, 0.5–0.7 and 0.4–0.6 lb/week, respectively.

table lookup by prepregnancy BMI category

Twin evidence boundary

The cited twin totals are 37–54 lb for normal BMI, 31–50 lb for overweight and 25–42 lb for obese. The table establishes no underweight-twin range or twin weekly-rate table, so the tool does not invent either.

Updated: August 2026

Example Scenarios

A 165 cm, 62 kg prepregnancy entry produces BMI 22.8 and retains both the 25–35 lb total and 0.8–1.0 lb/week second/third-trimester interval.

Height: 165 cmPrepregnancy weight: 62 kgType: Singleton

Cited total range: 25–35 lb

The twin table returns 37–54 lb total and explicitly says a weekly twin interval is not established in the cited table.

The calculator returns no cited range instead of reusing another BMI row or inventing an unsupported target.

Common Mistakes to Avoid

Reducing the official weekly interval to one point

Keep the full cited singleton interval and its first-trimester assumption visible.

Inventing an underweight-twin range or twin weekly rate

Return the missing-evidence state and discuss an individualized plan with the prenatal care team.

FAQ

Use prepregnancy measurements. The BMI categories in the cited guidance are based on BMI before pregnancy, not current pregnancy weight.

Underweight 28–40 lb, normal 25–35 lb, overweight 15–25 lb and obese 11–20 lb, with separate second/third-trimester intervals shown in the result.

The cited IOM/ACOG twin table lists ranges only for normal, overweight and obese BMI categories. The calculator preserves that evidence gap.

No. The cited twin summary supplies total ranges but not a twin weekly-rate table, so singleton weekly intervals are not reused.

No. It is a population guideline lookup. Clinical judgment, health history and pregnancy progress can change individualized guidance.

About Pregnancy Weight Gain Calculator

Enter prepregnancy height and weight, then choose singleton or twins. The result preserves the cited range and evidence limits; it is not a personal target or fetal-growth assessment.