Pregnancy Health

Pregnancy Weight
Gain Calculator

Track your pregnancy weight gain against IOM guidelines. Supports single and twin pregnancies with week-by-week recommended ranges based on your pre-pregnancy BMI.

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🍼 Pregnant with Twins?

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Pre-Pregnancy Weight

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Weight Gained

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kg so far

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Pre-BMI

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Pre-Preg BMI

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📈 Week-by-Week Weight Gain Tracker

📋 IOM Recommended Weight Gain Guidelines

Source: Institute of Medicine (IOM) 2009 guidelines, adopted by WHO and ACOG. These are evidence-based recommendations — always discuss with your OB/GYN or midwife for personalized guidance.

🔬 Where Does Pregnancy Weight Go?

A typical full-term pregnancy weight gain of ~12 kg breaks down into these components:

Understanding Pregnancy Weight Gain

Healthy pregnancy weight gain is associated with better outcomes for both mother and baby. Gaining too little can increase the risk of preterm birth and low birth weight, while gaining too much raises the risk of gestational diabetes, pre-eclampsia, and the need for C-section.

IOM Guidelines by Pre-Pregnancy BMI

Pre-Pregnancy BMI Categories (IOM 2009): Underweight (BMI < 18.5): 12.5–18.0 kg total (0.44–0.58 kg/week in 2nd & 3rd tri) Normal weight (18.5–24.9): 11.5–16.0 kg total (0.35–0.50 kg/week) Overweight (25.0–29.9): 7.0–11.5 kg total (0.23–0.33 kg/week) Obese (BMI ≥ 30): 5.0–9.0 kg total (0.17–0.27 kg/week) Twin Pregnancy (add to above): Normal weight: 16.8–24.5 kg Overweight: 14.1–22.7 kg Obese: 11.3–19.1 kg

Trimester-by-Trimester Weight Gain

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First Trimester (1–13)

Most women gain just 1–2 kg. Some lose weight due to nausea. Major organ formation occurs — nutrient quality matters more than quantity.

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Second Trimester (14–27)

Appetite increases. Baby grows rapidly. Aim for 0.35–0.50 kg per week (normal BMI). This is when most weight gain occurs.

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Third Trimester (28–40)

Baby gains most weight now. Continue steady gain. Swelling (edema) is normal and contributes to total weight.

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After Delivery

Most women lose 5–6 kg immediately at birth (baby + fluid + placenta). The remaining 5–7 kg is lost gradually over 6 months postpartum.

Frequently Asked Questions

What if I'm gaining more or less than recommended?

These are guidelines, not strict rules. Every pregnancy is different. If you're consistently above or below the recommended range, discuss it with your healthcare provider — they can assess whether dietary adjustments or further monitoring is needed. Short-term fluctuations of 1–2 kg are normal due to water retention, bowel habits, and measurement differences.

Should I diet during pregnancy if I'm gaining too much?

No — caloric restriction during pregnancy is not recommended and can deprive the baby of essential nutrients. Instead, focus on nutrient-dense foods, reduce empty calories (sugary drinks, processed foods), and engage in gentle exercise if your healthcare provider approves. Gestational weight gain above guidelines is common and manageable through healthy habits.

Do obese women need to gain weight during pregnancy?

Yes — even women with obesity (BMI ≥ 30) should gain 5–9 kg during pregnancy according to IOM guidelines. Some research suggests that certain obese women with very high BMIs may be able to gain less (or even no weight) safely, but this should only be managed under close medical supervision. Never try to lose weight during pregnancy without medical guidance.

How much extra calories do I need during pregnancy?

First trimester: no extra calories needed. Second trimester: approximately 340 extra calories/day. Third trimester: approximately 450 extra calories/day. The saying "eating for two" is a myth — you're eating for 1.1 people. Focus on food quality over quantity: extra protein, folate, iron, calcium, DHA, and iodine are priority nutrients.

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