How Much Weight Should I Gain?
It depends entirely on your Pre-Pregnancy BMI. Gaining within these guidelines is proven to reduce risks for both mom (gestational diabetes, c-section) and baby (premature birth, high birth weight).
| Pre-Pregnancy BMI | Category | Recommended Gain (Single) | Recommended Gain (Twins) |
|---|---|---|---|
| < 18.5 | Underweight | 28 - 40 lbs | Consult Doctor |
| 18.5 - 24.9 | Normal Weight | 25 - 35 lbs | 37 - 54 lbs |
| 25.0 - 29.9 | Overweight | 15 - 25 lbs | 31 - 50 lbs |
| ≥ 30.0 | Obese | 11 - 20 lbs | 25 - 42 lbs |
Source: Institute of Medicine (IOM) 2009 Guidelines
Where Does the Weight Go?
If you gain 30 lbs, only a fraction of that is continuous fat storage. Most of it is biological support for the baby. Here is a typical breakdown for a 30 lb gain:
7.5 lbs
The Baby
4.0 lbs
Blood Volume
2.0 lbs
Amniotic Fluid
7.0 lbs
Fat Stores
1.5 lbs
Placenta
8.0 lbs
Uterus, Breasts & Fluids
Frequently Asked Questions
I gained 10 lbs in the first trimester. Is that bad?
IOM guidelines suggest 1-4.5 lbs for the first trimester, so 10 lbs is higher than average. However, weight gain is often non-linear (growth spurts happen!). Don't panic. Focus on steady, nutrient-dense nutrition in the 2nd trimester to level out your curve.
I am overweight (BMI 28). Should I diet?
Never diet to lose weight during pregnancy unless strictly supervised by your doctor. Restriction can harm the baby's development. The goal is to restrict your gain to the recommended 15-25 lbs range, not to lose pounds.
How does it change for twins?
Twin moms need to gain significantly more (37-54 lbs for normal BMI) to support two placentas and two growing babies. Nutrient needs increase, so don't be afraid of the higher number on the scale—it is necessary for healthy twins!
Tools & Data Verified by the EverydayCalculators Medical Research Team.
Last updated: January 2026.