The article is professionally reviewed by Dr Phạm Thị Yến, Specialist Level I - Department of Obstetrics and Gynecology - Vinmec Hai Phong International Hospital.
Weight gain during pregnancy reflects not only the mother's health but also the fetus's development in the womb. The estimated weight gain during pregnancy is based on the mother's pre-pregnancy weight.
1. What is a reasonable weight gain during pregnancy?
Weight gain during pregnancy depends on factors such as the fetus's weight, placenta, amniotic fluid, increased blood volume, fat, body tissues, and fluids. According to the World Health Organization (WHO), weight gain is estimated based on the Body Mass Index (BMI) before pregnancy:
BMI = weight (kg) / [height × height] (m)
- If the mother has a normal weight before pregnancy (BMI 18.5–24.9): the ideal weight gain is 10–12 kg, distributed as:
First trimester: 1 kg
Second trimester: 4–5 kg
Third trimester: 5–6 kg - If the mother is underweight (BMI < 18.5): the weight gain should be about 25% of the pre-pregnancy weight, typically 12.7–18.3 kg.
- If the mother is overweight or obese (BMI ≥ 25): the ideal weight gain is about 15% of the pre-pregnancy weight, typically 7–11.3 kg.
- In cases of twin pregnancy: weight gain should be approximately 16–20.5 kg.
2. Some notes to help mothers monitor weight during pregnancy
Pregnant women should regularly check their weight every month and consult a doctor if they notice any unusual weight gain or loss.
Starting from the 4th month of pregnancy, mothers usually gain about 1.5–2 kg per month. If the weight gain is less than 1 kg or exceeds 3 kg, they should see a doctor immediately, as both excessive and insufficient weight gain can negatively affect the health of the mother and baby. Excessive weight gain can lead to preeclampsia, gestational diabetes, and increased risk of cesarean delivery, while insufficient weight gain can result in intrauterine growth restriction, fetal malnutrition, and a higher risk of preterm birth.
To maintain reasonable weight gain, pregnant women need to pay attention to their diet. During a normal pregnancy, the mother needs an additional 80,000 calories throughout the pregnancy, equivalent to an average of 285 calories per day over 280 days. Therefore, mothers should consume nutrient-rich foods without excessive calories, such as sugary drinks, snacks, or overly fatty foods. It is important to choose nutritious foods from clear sources that ensure food safety. Mothers should also include vegetables and fruits in their diet, as they are rich in nutrients and provide essential vitamins and minerals for the fetus's development.
Pregnant women should ensure adequate rest, sufficient sleep, and avoid stress or anxiety. Furthermore, they should limit the use of stimulants such as alcohol, tobacco, and spicy or hot seasonings.
If there are any unusual symptoms, pregnant women should seek consultation and examination from a specialist.
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