How much weight should I have gained by each trimester?

For a normal pre-pregnancy BMI, gain is small in the first trimester (often 1-4 lb), then roughly 1 lb per week through the second and third trimesters, reaching a total around 25-35 lb. Ranges shift with your starting BMI.

What is a normal pregnancy weight gain chart?

A typical chart shows cumulative gain rising slowly at first, then climbing steadily after the first trimester, ending within the IOM/ACOG total band for your pre-pregnancy BMI.

Why did I barely gain or lose weight in the first trimester?

That's common. Nausea and a small first-trimester requirement mean little gain early on. Most weight is added in the second and third trimesters.

Where does pregnancy weight go?

It's distributed across the baby, placenta, amniotic fluid, increased blood and fluid, the enlarged uterus and breasts, and some maternal fat stores that support breastfeeding, not just fat.

How do I find my own recommended range?

Use the pregnancy weight gain calculator: enter your pre-pregnancy height and weight and your current week to see your BMI category, total range, and an estimate of where your cumulative gain might be.

Pregnancy Weight Gain Chart by Trimester and BMI

By Mustafa Bilgic · Updated June 2026 · Based on the IOM (2009) gestational weight-gain guidelines as summarized by ACOG and the CDC.

Educational information, not medical advice. The charts below use published IOM/ACOG ranges for general guidance. Every pregnancy is individual, and your obstetric provider's advice always comes first. Operator: Mustafa Bilgic.

This pregnancy weight gain chart shows roughly how weight gain is distributed across the three trimesters, and how the recommended total changes with your pre-pregnancy BMI. Most weight is gained in the second and third trimesters — the first trimester adds only a little. Use the visual below to see the typical pattern, then run the numbers for your own situation with our pregnancy weight gain calculator.

The trimester chart (normal pre-pregnancy BMI)

The cumulative line below illustrates a typical 25–35 lb pattern for someone starting at a normal pre-pregnancy BMI: a small rise in the first trimester, then a steady climb of roughly 1 lb per week through the second and third trimesters.

Typical cumulative gain (normal BMI) Recommended band (25–35 lb at term)

Illustrative pattern only, scaled to a normal pre-pregnancy BMI. Individual gain varies; follow your provider's guidance.

Recommended total weight gain by pre-pregnancy BMI

The IOM/ACOG total recommendations depend on the BMI you had before pregnancy:

Pre-pregnancy BMI	Category	Single baby
Below 18.5	Underweight	28–40 lb
18.5–24.9	Normal weight	25–35 lb
25.0–29.9	Overweight	15–25 lb
30.0 and above	Obese	11–20 lb

Want your own number? The pregnancy weight gain calculator takes your pre-pregnancy height and weight and your current week, and shows your category, total range, and approximate cumulative gain to date.

How gain is distributed by trimester

For a typical single pregnancy at a normal starting BMI, the rough breakdown is:

Trimester	Weeks	Approx. gain
First	1–13	Small — often about 1–4 lb total
Second	14–27	Steadier — roughly 1 lb/week
Third	28–40	Continues — roughly 1 lb/week, may slow near term

Key point: Don't be alarmed by little gain (or even minor loss from morning sickness) in the first trimester — that's common. Most of the recommended total is gained later, at a steadier weekly pace.

Where does the weight actually go?

Pregnancy weight is far more than fat stores — it supports the baby and the changes your body makes. A commonly cited approximate breakdown near term for a single pregnancy includes the baby (about 7–8 lb), the placenta, amniotic fluid, increased blood and fluid volume, a larger uterus and breasts, and some maternal fat stores that help support breastfeeding. The exact split varies, but it shows that healthy gain is doing important work.

Twin pregnancies

Carrying twins means a higher recommended total. For a normal pre-pregnancy BMI, IOM/ACOG cite roughly 37–54 lb, with overweight (31–50 lb) and obese (25–42 lb) categories adjusted accordingly. For the underweight category with twins, guidance is individualized — ask your provider.

How to track your gain

Weigh under consistent conditions and focus on the trend across appointments, not day-to-day numbers.
Bring questions to your prenatal visits — your provider tracks your gain against your personal target.
Don't chase a number — the ranges are guides, and being slightly outside them is common and usually fine if your provider is satisfied.

Mustafa Bilgic

Operator of WeightGain.us, based in Adıyaman, Türkiye. Mustafa is an independent publisher, not a medical professional; all ranges here come from the published IOM/ACOG/CDC guidelines and are attributed to those bodies. For personal advice about your pregnancy, consult your obstetric provider.

When to call your provider: sudden or rapid weight gain, very little gain over time, or significant swelling can need evaluation. Never restrict gestational weight gain by dieting without medical supervision.

Frequently asked questions

How much weight should I have gained by each trimester?: For a normal pre-pregnancy BMI, gain is small in the first trimester (often 1–4 lb), then roughly 1 lb per week through the second and third trimesters, reaching a total around 25–35 lb. Ranges shift with your starting BMI.
What is a normal pregnancy weight gain chart?: A typical chart shows cumulative gain rising slowly at first, then climbing steadily after the first trimester, ending within the IOM/ACOG total band for your pre-pregnancy BMI. The chart on this page illustrates the normal-BMI pattern.
Why did I barely gain (or lose) weight in the first trimester?: That's common. Nausea and a small first-trimester requirement mean little gain early on. Most weight is added in the second and third trimesters.
Where does pregnancy weight go?: It's distributed across the baby, placenta, amniotic fluid, increased blood and fluid, the enlarged uterus and breasts, and some maternal fat stores that support breastfeeding, not just fat.
How do I find my own recommended range?: Use our pregnancy weight gain calculator: enter your pre-pregnancy height and weight and your current week to see your BMI category, total range, and an estimate of where your cumulative gain might be.

Keep reading

References

Sources: ACOG — Weight Gain During Pregnancy · CDC — Weight Gain During Pregnancy · Institute of Medicine (2009), Weight Gain During Pregnancy (NIH/NCBI) · MedlinePlus (NIH) — Pregnancy and Nutrition.