Pregnancy Weight Gain: What's Normal by Trimester

Pregnancy weight gain is one of those topics where everyone has an opinion and very few have the math. The official ranges are surprisingly tight.

Google this topic and you will get a hundred answers, half of them wrong. Here is the version that holds up. Pregnancy weight gain is one of those topics where everyone has an opinion and very few have the math. The official ranges are surprisingly tight.

Total gain by pre-pregnancy BMI

Underweight: 12.5–18 kg. Normal: 11.5–16 kg. Overweight: 7–11.5 kg. Obese: 5–9 kg.

Trimester pattern

T1: 0.5–2 kg total. T2 + T3: ~0.4 kg/week. Gain accelerates in the middle and tapers near term.

Where the weight goes

Baby ~3.5 kg, placenta ~0.7 kg, fluid ~1 kg, blood volume ~1.5 kg, breast tissue ~0.5 kg, uterus ~1 kg, fat stores ~3–4 kg.

When to worry

Sudden gain (3+ kg in a week) can signal preeclampsia. Very little gain after T1 needs a doctor's check.

Pro tips

  • Calories needed: BMR + 0 in T1, +340/day in T2, +450/day in T3.
  • Quality matters — vegetables, protein and complex carbs beat 'eating for two' on ice cream.

Frequently asked questions

Is twin pregnancy gain different? Yes — add ~5 kg to the recommended range.

How fast should I lose it after? 0.5–1 kg/week if breastfeeding, otherwise slower. Patience > crash dieting.

Run your own numbers before you trust a rule of thumb. Two minutes saves a lot of regret.

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