How much weight should you gain during pregnancy?

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Ngày cập nhật gần nhất: 15/4/2026

Each person is a unique individual with different genetic factors, gender, age, environment, diet, and lifestyle, so each person's weight gain during pregnancy will vary.

Typically, a woman only gains about 10 – 15kg throughout the 40 weeks of pregnancy. In cases of multiple pregnancies or complications during pregnancy, weight may vary. During the first trimester, some pregnant women usually gain weight lightly, while others may lose weight due to morning sickness or changes in diet. However, from the second trimester onwards, most pregnant women will regain their initial weight and gradually gain more.

Eating for two?

The notion of eating for two is actually an ancient belief with no scientific basis. In fact, doubling the food intake for the mother is not only unnecessary but also problematic for both the mother and the baby. Instead of focusing on increasing the quantity of food, mothers should pay attention to the nutritional quality of the food.

Mothers only need to supplement about 10% more calories into their bodies.

In the first trimester: Mothers need to supplement 420 calories/day – equivalent to 1 full glass of milk

Second trimester: Mothers need to supplement 1050 calories/day – equivalent to a handful of nuts and a few slices of fruit.

Third trimester: Mothers need to supplement 1255 calories/day – equivalent to various fruits and a slice of bread.

Why do you gain weight?

Weight gain during pregnancy can be evaluated through two aspects: The mother's weight gain and the baby's weight gain. A pregnant woman may be considered to have normal weight gain if her body gains about 3kg during pregnancy, focusing on areas like thighs, hips, buttocks, and arms – these are energy reserves for breastfeeding later on.

The mother's body gains weight during pregnancy due to:

Increased blood circulation

Enhanced water and fluid retention.

Increased breast size.

Increased size of the uterus.

Appearance of amniotic sac and placenta.

That's why most doctors carefully monitor the mother's weight because sudden changes in the mother's weight can be a cause of some pregnancy complications. It is best for pregnant women to create a chart to regularly monitor their weight at a specific time of day.

You should visit a doctor for assessment if you gain more than 1.5kg per week during the middle months or 900 grams per week in the later months of pregnancy.

Ideal weight gain:

First trimester: 900 grams – 1.8kg per week

Second trimester: 500 grams per week (5 -6kg over 3 months )

Third trimester: 400 grams per week (3 – 5kg over 3 months )

What about BMI?

In addition, mothers can rely on BMI (body mass index) as a criterion to evaluate the ideal weight gain.

BMI = body weight/height squared (calculated in meters)

If the BMI is in the range of 18.5 – 26, it is considered healthy. If it is too low or too high, pregnant women should consult a doctor to reconsider their diet.

How long does it take to lose weight?

Many experts agree that if it takes 9 months to gain weight, it may take the same amount of time to lose it. However, some mothers lose weight very quickly and return to their pre-pregnancy shape within a few weeks of giving birth, while others take longer.

The principles of weight loss are the same: the more you eat, the more you must exercise to burn energy.

Is dieting recommended?

Dieting during pregnancy leads to nutritional deficiencies affecting the fetus and the baby's development. Maternal dieting during pregnancy also increases the risk of infant mortality or low birth weight.