Pregnancy weight gain guidelines by pre-pregnancy BMI

Recommended pregnancy weight gain is primarily organized by pre-pregnancy BMI and whether the pregnancy is singleton or twin. The ranges below are general guidance for populations, not personal medical targets.

Use the BMI category from before pregnancy, not a category reassigned from weight gained during pregnancy. Your prenatal care team may use additional information that this guide and calculator do not have.

CDC and the National Academies publish these total-gain ranges for a pregnancy with one baby.

After the first trimester, published guidance also gives an approximate rate context. These rates are not a personal weekly target, a cumulative band, or a diagnosis.

Weight does not need to follow a straight line. A rate context helps explain a published recommendation; it does not independently determine whether an individual pregnancy is healthy.

A commonly cited approximate first-trimester context is about 0.5–2.0 kg (1.1–4.4 lb). It is not a requirement that every person gain this amount, and it should not be used to judge a pregnancy without clinical context.

CDC publishes these twin-pregnancy ranges by pre-pregnancy BMI:

The underweight twin range is a CDC-published exception in the public table; it is not presented here as a new National Academies or IOM recommendation.

There is no single unified numeric target for triplets and higher-order pregnancies in the sources used here. Individual provider guidance is more appropriate than extending a singleton or twin table.

Pre-pregnancy BMI is used because it describes the starting context before pregnancy-related weight changes. Reclassifying someone by current pregnancy weight would mix the input with the outcome being interpreted.

The published categories are based on pre-pregnancy BMI, not a judgment about body size during pregnancy. They help organize population guidance before pregnancy weight, fluid, and fetal growth change the measurement.

Clinical judgment may consider pregnancy health, fetal growth, medical history, symptoms, nutrition, and information unavailable to this page. A care team may therefore use a different interpretation from a published range.

Current CDC guidance continues to publish the BMI-based framework derived largely from the 2009 National Academies recommendations, with a separately published underweight-twin exception. A 2026 workshop reviewed evidence and policy questions; it is not a replacement guideline.

Use the Pregnancy Weight Gain Calculator with height, pre-pregnancy weight, pregnancy type, and any optional current-weight record you already have. The result is a reference calculation, not a personal target.

Each source is linked to the specific claim it supports. These sources do not endorse Pregnancy Metrics.

1. CDC — Weight Gain During Pregnancy

   Provides the singleton and twin pregnancy weight-gain ranges by pre-pregnancy BMI and explains the role of pregnancy type.

2. ACOG — Weight Gain During Pregnancy

   Explains pre-pregnancy BMI categories, singleton ranges, later-pregnancy rate context, and why individual care may differ.

3. National Academies — Weight Gain During Pregnancy: Reexamining the Guidelines

   Provides the 2009 evidence and recommendations underlying the commonly used pre-pregnancy BMI categories and total gain ranges.

4. NCBI Bookshelf — Summary / Table S-1

   Summarizes the National Academies recommendations, including singleton total ranges and second- and third-trimester rate context.

5. National Academies — 2026 Workshop on Weight Gain During Pregnancy

   Documents that current evidence and policy were reviewed in 2026; it is an evidence discussion and not a replacement guideline.

This guide does not provide diet, calorie, exercise, weight-loss, fetal-growth, fluid, preeclampsia, diabetes, diagnosis, or treatment advice. It cannot determine whether an individual pregnancy is healthy or whether weight change has a specific clinical cause.

Use current pregnancy records and qualified healthcare guidance for individual care.