How much weight should I gain during pregnancy?

Recommended pregnancy weight gain depends on your pre-pregnancy BMI. For a healthy BMI (18.5-24.9), the recommendation is 11.5 to 16kg total. Underweight women (BMI under 18.5) should gain 12.5 to 18kg. Overweight women (BMI 25-29.9) should gain 7 to 11.5kg. Obese women (BMI 30+) should gain 5 to 9kg. These guidelines are from the Institute of Medicine (IOM) and are used in Australian practice.

How much weight should I gain per week in pregnancy?

In the first trimester, weight gain is minimal — about 0.5 to 2kg total. From the second trimester onwards, the recommended rate is about 0.4kg per week for healthy-weight women, 0.5kg per week if underweight, 0.3kg per week if overweight, and 0.2kg per week if obese. These are averages — some fluctuation week to week is normal.

Is it safe to lose weight during pregnancy?

Intentional weight loss during pregnancy is not recommended. However, some women with a higher BMI may gain less than the guidelines suggest, and this can be acceptable if the baby is growing well. If you are concerned about your weight gain, discuss it with your GP or midwife. They can monitor your baby's growth with fundal height measurements and ultrasound.

Pregnancy Weight Gain Calculator

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Singleton Twins

Gaining more than recommended can increase risk of gestational diabetes, pre-eclampsia, larger baby (macrosomia), and caesarean delivery. Focus on nutrient-dense foods, stay active (walking, swimming), and discuss with your midwife or GP.

Gaining less than recommended may increase risk of preterm birth or low birth weight. This is especially important if you were underweight before pregnancy. If you're struggling with appetite or nausea, speak with your GP or midwife.

Do not diet during pregnancy. Focus on eating well rather than restricting intake.

These recommendations are based on the Institute of Medicine (IOM) 2009 guidelines, which are endorsed by the Royal Australian and New Zealand College of Obstetricians and Gynaecologists (RANZCOG) and used in Australian and NZ antenatal care.

BMI categories use the WHO classification: underweight <18.5, healthy 18.5–24.9, overweight 25–29.9, obese ≥30.

Pregnancy Weight Gain

Weekly rate from 2nd trimester onwards

Where does the weight go?