Recommended total weight gain: one baby
The four BMI categories below are the ones used by the Institute of Medicine (IOM, now part of the National Academies of Sciences, Engineering, and Medicine) and reproduced by the CDC. Use your weight and height before pregnancy, not your current weight.
Recommended total weight gain in a singleton pregnancy by pre-pregnancy BMI category
| Pre-pregnancy BMI category |
BMI |
Recommended total gain |
| Underweight |
Below 18.5 |
28–40 lb (12.5–18 kg) |
| Normal weight |
18.5–24.9 |
25–35 lb (11.5–16 kg) |
| Overweight |
25.0–29.9 |
15–25 lb (7–11.5 kg) |
| Obese |
30.0 or higher |
11–20 lb (5–9 kg) |
Source: CDC — Weight Gain During Pregnancy and Institute of Medicine (2009), Table 7-3. Checked 2026-11-10.
Weekly rate after the first trimester
The IOM guidance assumes a small, fairly modest gain in the first trimester for every BMI category, then a steady weekly gain through the second and third trimesters. The weekly figure is a rate, not a target for every single week.
Assumed first-trimester gain and recommended weekly gain in the second and third trimesters by BMI category
| BMI category |
Assumed first-trimester gain |
Second and third trimester |
| Underweight (below 18.5) |
1.1–4.4 lb (0.5–2 kg) in total |
About 1 lb per week (range 1–1.3 lb) |
| Normal weight (18.5–24.9) |
1.1–4.4 lb (0.5–2 kg) in total |
About 1 lb per week (range 0.8–1 lb) |
| Overweight (25.0–29.9) |
1.1–4.4 lb (0.5–2 kg) in total |
About 0.6 lb per week (range 0.5–0.7 lb) |
| Obese (30.0 or higher) |
1.1–4.4 lb (0.5–2 kg) in total |
About 0.5 lb per week (range 0.4–0.6 lb) |
Source: Institute of Medicine and National Research Council, Weight Gain During Pregnancy (2009), Table 7-3. Checked 2026-11-10.
Recommended total weight gain: twins
A twin pregnancy has higher recommended ranges because two babies, two placentas and a larger blood volume all add weight. The CDC publishes a separate table for twins.
Recommended total weight gain in a twin pregnancy by pre-pregnancy BMI category
| Pre-pregnancy BMI category |
BMI |
Recommended total gain |
| Underweight |
Below 18.5 |
50–62 lb |
| Normal weight |
18.5–24.9 |
37–54 lb |
| Overweight |
25.0–29.9 |
31–50 lb |
| Obese |
30.0–39.9 |
25–42 lb |
Source: CDC — Weight Gain During Pregnancy. Checked 2026-11-10. The CDC notes that all of these ranges come from the Institute of Medicine except the underweight twin range.
If you are expecting triplets or more, the CDC directs you to your health care provider for weight gain goals rather than to a published range.
How to read this chart
BMI = pre-pregnancy weight in kg ÷ (height in metres × height in metres)
Work out your BMI from your weight before you became pregnant. The category is fixed for the whole pregnancy, even though your current weight changes. For UK readers, the NHS notes that most pregnant women gain between 10 kg and 12.5 kg (22 lb to 28 lb) overall and put on most of that weight after week 20 — a useful sanity check, but not a substitute for a BMI-specific range.
If you already know your due date, our due date calculator will show how many weeks pregnant you are today, which is the number your midwife or doctor will use when they plot your weight against these ranges.
These are population ranges, not a prescription. Individual weight gain varies with your starting weight, your baby's growth, whether you are carrying one baby or more, and conditions such as severe nausea or gestational diabetes. Your obstetric team can set a target that fits your pregnancy, and may adjust it as the pregnancy progresses.
How we built this chart
We copied the ranges from two public sources rather than recalculating them: the CDC's weight gain page, which reproduces the IOM recommendations for singleton and twin pregnancies, and the IOM/NRC report table itself, which also publishes the assumed first-trimester gain and the second- and third-trimester weekly rates. We kept the source units (pounds and kilograms) and did not add decimal precision beyond what the sources print.
Sources used on this page:
All three sources were checked on 2026-11-10. If a source had not stated a figure, we left it out rather than filling the gap.
Frequently asked questions
How is pre-pregnancy BMI used in this chart?
The chart uses the BMI category you were in before pregnancy, not your current BMI. BMI is your pre-pregnancy weight in kilograms divided by your height in metres squared. The four categories are underweight (below 18.5), normal weight (18.5 to 24.9), overweight (25.0 to 29.9) and obese (30.0 or higher).
Is the recommended weight gain the same for twins?
No. Twin pregnancies have higher recommended ranges: 50 to 62 lb for underweight, 37 to 54 lb for normal weight, 31 to 50 lb for overweight and 25 to 42 lb for obese. The CDC notes that all of these come from the Institute of Medicine except the underweight twin range.
How much weight gain is normal in the first trimester?
The Institute of Medicine model assumes a total first-trimester gain of 1.1 to 4.4 lb (0.5 to 2 kg) for every BMI category. After that, recommended gain is expressed as a weekly rate for the second and third trimesters rather than a fixed amount for each week.
Can I use this chart to decide my own weight gain target?
No. These are population-level ranges, and individual needs vary with your health, your baby's growth and how the pregnancy progresses. Your midwife or obstetrician is the person who can set and adjust a target for you, including if you are carrying more than one baby or have a medical condition.
Disclaimer
This page is educational and is not medical advice. It does not diagnose anything and does not replace an antenatal appointment. If you are losing weight, gaining very quickly, unable to keep food down, or worried about your weight or your baby's growth, contact your midwife, obstetrician or urgent care service.