Pregnancy weight gain guide
Pregnancy weight gain guidelines by pre-pregnancy BMI
Pregnancy weight-gain recommendations depend mainly on your pre-pregnancy body mass index (BMI) and whether you are carrying one baby or twins. The published ranges are general population guidance, not a number every individual pregnancy must hit exactly.
The short answer
For one baby, the commonly published total ranges run from 11–20 lb at a pre-pregnancy BMI of 30 or above to 28–40 lb below a BMI of 18.5. Twin ranges are higher and use a separate table. Start with the BMI category from before pregnancy, then use the table for the pregnancy type.
These ranges describe population guidance across pregnancy. They do not require weight to rise by the same amount every week and do not replace an individualized recommendation from your care team.
Weight-gain ranges for one baby
CDC and the National Academies publish these total-gain ranges for a singleton pregnancy:
| Pre-pregnancy BMI | Category | Total gain (lb) | Total gain (kg) |
|---|---|---|---|
| <18.5 | Underweight | 28–40 lb | 12.5–18 kg |
| 18.5–24.9 | Normal | 25–35 lb | 11.5–16 kg |
| 25.0–29.9 | Overweight | 15–25 lb | 7–11.5 kg |
| ≥30 | Obesity | 11–20 lb | 5–9 kg |
Weight-gain ranges for twins
CDC publishes separate total ranges for a twin pregnancy. A singleton range should not simply be doubled.
| Category | Total gain (lb) | Approximate kg |
|---|---|---|
| Underweight | 50–62 lb | ~22.7–28.1 kg |
| Normal | 37–54 lb | ~16.8–24.5 kg |
| Overweight | 31–50 lb | ~14.1–22.7 kg |
| Obesity | 25–42 lb | ~11.3–19.1 kg |
The underweight twin range is included in CDC’s public table. It is presented here as CDC guidance rather than relabeled as a separate National Academies recommendation.
How weight gain changes across pregnancy
A commonly used first-trimester context is about 0.5–2.0 kg (1.1–4.4 lb) in total. For the second and third trimesters, published guidance also provides approximate weekly rate ranges based on pre-pregnancy BMI.
| Pre-pregnancy category | kg per week | lb per week |
|---|---|---|
| Underweight | 0.44–0.58 kg/wk | 1.0–1.3 lb/wk |
| Normal | 0.35–0.50 kg/wk | 0.8–1.0 lb/wk |
| Overweight | 0.23–0.33 kg/wk | 0.5–0.7 lb/wk |
| Obesity | 0.17–0.27 kg/wk | 0.4–0.6 lb/wk |
These later-pregnancy rates are rate context, not a guaranteed weekly trajectory, an official week-by-week cumulative band, a personal target, or a diagnosis.
Does weight need to increase every week?
No. Weight gain does not have to follow a perfectly straight line from one week to the next. Day-to-day and week-to-week body weight can vary, while published rate guidance describes a broader population pattern rather than requiring every measurement to rise by the same amount.
Rapid, large, unexpected, or clinically concerning changes need interpretation from the prenatal care team. A general table cannot diagnose a cause or prescribe what to do.
Why pre-pregnancy BMI is used
The guideline categories use the starting BMI before pregnancy because current pregnancy weight already includes pregnancy-related change. The category organizes population guidance; it is not a judgment about someone’s body.
What if my care team gives different guidance?
Individual advice can differ because a clinician can consider information this page does not have, including health history, pregnancy complications, fetal growth, symptoms, nutrition, and other clinical findings. Your care team’s individualized guidance takes priority over a general online reference.
What about triplets or higher-order pregnancies?
The sources used here do not provide one general numeric target equivalent to the singleton and twin tables for triplets or higher-order pregnancies. Use individualized guidance rather than extending or multiplying either table.
Use the calculator
The Pregnancy Weight Gain Calculator can calculate the pre-pregnancy BMI category, show the singleton or twin total range, and add optional current-weight arithmetic. For supported singleton results, it can also show the site’s transparent derived reference—not an official CDC week-by-week band or individualized medical target.
Official sources
Current public guidance still relies substantially on the National Academies framework used by CDC. These sources support the ranges and rate context; they do not review or endorse Pregnancy Metrics.
- CDC — Weight Gain During Pregnancy
Publishes total weight-gain ranges for singleton and twin pregnancies by pre-pregnancy BMI.
- ACOG — Weight Gain During Pregnancy
Explains BMI-based recommendations, later-pregnancy rate context, and individualized clinical care.
- National Academies — Weight Gain During Pregnancy: Reexamining the Guidelines
Provides the evidence framework behind the commonly used 2009 recommendations.
- NCBI Bookshelf — Summary / Table S-1
Summarizes singleton total ranges and second- and third-trimester rate guidance.