Find your recommended weight gain range during pregnancy, based on your pre-pregnancy BMI and official IOM guidelines.
Reviewed by Sarah Mitchell, BSc Nutrition · Last updated: July 2026
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Leave blank to just see your full-pregnancy target range.
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Recommended total weight gain (full pregnancy)
Your Pre-Pregnancy BMI Category
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Institute of Medicine (IOM), 2009 guidelines
Estimated Gain-to-Date (Week )
A rough guide only — actual week-to-week gain varies and isn't linear, especially early on.
Typical Weekly Pace (2nd & 3rd Trimester)
Next step: These are population-level guidelines —
talk to your OB/GYN or midwife about what's right for your individual pregnancy.
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How Pregnancy Weight Gain Recommendations Work
The most widely used guidelines come from the Institute of Medicine (IOM), now part of the National Academies of Sciences, Engineering, and Medicine. Rather than a single target, the IOM recommends a range based on your pre-pregnancy BMI — since starting weight affects how much additional weight supports a healthy pregnancy.
💡 Important: These figures are general population guidelines, not a diagnosis or a prescription. Your healthcare provider may recommend something different based on your health history, whether you're carrying twins, or other individual factors.
Recommended Total Weight Gain — Singleton Pregnancy
Pre-Pregnancy BMI
Category
Recommended Total Gain
Below 18.5
Underweight
12.5–18 kg (28–40 lb)
18.5–24.9
Normal weight
11.5–16 kg (25–35 lb)
25.0–29.9
Overweight
7–11.5 kg (15–25 lb)
30.0 and above
Obese
5–9 kg (11–20 lb)
Recommended Total Weight Gain — Twin Pregnancy
Pre-Pregnancy BMI
Category
Recommended Total Gain
18.5–24.9
Normal weight
16.8–24.5 kg (37–54 lb)
25.0–29.9
Overweight
14.1–22.7 kg (31–50 lb)
30.0 and above
Obese
11.3–19.1 kg (25–42 lb)
The IOM has not established a specific range for underweight women carrying twins due to limited data — this should be discussed directly with your provider.
Weight Gain Isn't Even Across Pregnancy
Most of the recommended weight gain happens in the second and third trimesters, not the first:
First trimester: Typically just 0.5–2 kg (1–4.5 lb) total, regardless of starting BMI. Many people gain very little — or even lose weight briefly due to nausea.
Second and third trimester: A more steady weekly pace, which varies by pre-pregnancy BMI category (see the calculator above).
Week-to-week weight can also fluctuate due to fluid retention, so it's more useful to track the trend over several weeks than to react to any single weigh-in.
Where Does the Weight Actually Go?
Component
Approximate Weight
Baby
~3.2–3.6 kg (7–8 lb)
Placenta
~0.7 kg (1.5 lb)
Amniotic fluid
~0.9 kg (2 lb)
Increased blood volume
~1.4–1.8 kg (3–4 lb)
Breast tissue
~0.9 kg (2 lb)
Uterus growth
~0.9 kg (2 lb)
Fat, protein & fluid stores
~2.7–3.6 kg (6–8 lb)
These are typical approximate contributions for a singleton pregnancy at term — individual variation is normal.
What If My Weight Gain Is Outside the Range?
Gaining above or below the recommended range is common and doesn't automatically indicate a problem — but it's a good thing to raise with your OB/GYN or midwife, since they can interpret it in the context of your overall health, blood pressure, and how the pregnancy is progressing. This calculator is meant as a general reference point to bring to that conversation, not a replacement for it.
Frequently Asked Questions
It depends on your pre-pregnancy BMI. The Institute of Medicine recommends 12.5–18 kg (28–40 lb) for underweight women, 11.5–16 kg (25–35 lb) for normal weight, 7–11.5 kg (15–25 lb) for overweight, and 5–9 kg (11–20 lb) for obese pre-pregnancy BMI. These are general guidelines — your doctor may recommend a different target based on your individual health.
Yes. Most guidelines recommend only 0.5–2 kg (1–4.5 lb) total in the first trimester, with the majority of weight gain occurring steadily through the second and third trimesters. Week-to-week gain can also vary due to fluid retention, so looking at the overall trend over several weeks is more meaningful than any single weigh-in.
Recommended weight gain is higher for twin pregnancies. The IOM recommends 16.8–24.5 kg (37–54 lb) for normal weight, 14.1–22.7 kg (31–50 lb) for overweight, and 11.3–19.1 kg (25–42 lb) for obese pre-pregnancy BMI. There is no established IOM range for underweight women carrying twins — this should be discussed directly with your healthcare provider.
These ranges are population-level guidelines, not strict individual targets. Gaining outside the recommended range is common and does not automatically mean something is wrong, but it is worth discussing with your healthcare provider, since it can be associated with different risks for both parent and baby. Your doctor is best placed to interpret your specific situation.
📚 References
Institute of Medicine (US) and National Research Council (US) Committee to Reexamine IOM Pregnancy Weight Guidelines. (2009). Weight Gain During Pregnancy: Reexamining the Guidelines. National Academies Press. doi:10.17226/12584
American College of Obstetricians and Gynecologists (ACOG). Weight Gain During Pregnancy, Committee Opinion.
Not a substitute for professional medical advice. Always consult your OB/GYN or midwife about your individual pregnancy. Last updated July 2026.