Weight gain during pregnancy

Gaining weight is a normal part of pregnancy and essential for your baby’s healthy development. However, weight gain recommendations are specific to each expectant mother. They also vary according to trimester.

How much weight should you gain during pregnancy?

The amount of weight you should gain depends on your pre-pregnancy weight. Gaining more weight than necessary is not recommended.

Weight gain can be different from one woman to the next or even from one pregnancy to the next. That said, women carrying twins or multiples generally gain more.

Weight gain within the recommended range in the table below has been shown to lower the risk of complications (e.g., high blood pressure, gestational diabetes) and increase the likelihood of carrying to full-term and delivering a healthy baby.

Keep in mind that weight is just one consideration when it comes to having a healthy pregnancy and birth. Diet, physical activity, and sleep habits also have a major influence.

It’s important to note that the recommendation for women with a BMI of 30 or more is controversial. Several research teams have noted that obese women who gain less weight during pregnancy reduce their risk of high blood pressure, preeclampsia, gestational diabetes, and caesarean section delivery. The higher your BMI, the less weight you should gain during pregnancy.

Weight-loss diets are not recommended during pregnancy, however, as they may interfere with energy levels and nutritional intake, compromising fetal development and increasing fatigue.

Very obese women should work with a nutritionist to limit weight gain and ensure that they are getting all the nutrition they need for mother and the developing fetus.

Weight gain by trimester

Weight gain may look different from one trimester to the next. Women usually gain less weight in the first trimester, about 0.5 kg to 2 kg (1 lb to 4.5 lb).

However, some women may lose weight in the first trimester due to nausea, which reduces their appetite. Most of the time, they are able to regain the pounds they lost and reach their recommended weight once the nausea subsides.

In the second and third trimesters, weight gain varies from person to person. Broadly speaking, you can expect to put on about 225 g to 500 g (0.5 lb to 1 lb) per week during this period. Regular checkups allow your health care professional to track your progress and intervene if they see worrying weight gain or loss.

The most important thing you can do is to focus on eating a balanced diet. If you eat well and stay active throughout your pregnancy, you’ll gain a healthy amount of weight for you and your baby.

Weight gain distribution

Until your 15th week of pregnancy, any pounds you put on are essentially stores of protein (in your muscles) and fat (in your adipose tissue). These reserves will play an important role later in your pregnancy. Your baby will begin to grow exponentially in the second trimester.

Here’s an approximate breakdown of weight gain distribution during pregnancy:

• 37% blood, placenta, uterus, amniotic fluid, and other fluids
• 28% fetal growth
• 26% fat accumulation, which serves as an important energy reserve for the mother and fetus throughout the pregnancy
• 8% increased breast size

Weight-related concerns

Every woman experiences pregnancy and body changes differently. Some feel comfortable and enjoy their growing bellies and breasts. Others find it harder to accept these changes.

Pregnant women who are concerned about their weight, body image, or diet should talk to a health care professional (e.g., doctor, midwife, nutritionist, psychologist) to get the help they need to navigate this stage.

How long does it take to return to your pre-pregnancy weight?

As soon as a woman gives birth, she loses the weight associated with the baby, placenta, and amniotic fluid. Then, over the next six weeks or so, her uterus shrinks back to its normal size. Blood volume and swelling decrease, which also leads to weight loss. After this point, the new mother’s body gradually uses the fat reserves accumulated during pregnancy.

As with weight gain, weight loss can be different from one woman to the next and from one pregnancy to the next. Breastfeeding can speed up the process, but it’s completely normal for weight loss to take several months.

Even after losing all your pregnancy weight, your figure may not return to what it was before. Pregnancy transforms a person’s body—it’s to be expected! The most important thing to focus on is eating well and staying active.

Weight-loss diets are not recommended immediately after childbirth, as they put unnecessary strain on new mothers. If you’ve just had a baby, you need calories to recover. And if you’re breastfeeding, you need calories to produce milk.

For tips on healthy eating, consult Canada’s food guide. A nutritionist can also provide practical advice on how to reach a healthy weight.

Things to keep in mind

• Gaining too little or too much weight increases the risk of complications during pregnancy and childbirth.
• Good eating habits and regular exercise are important for a healthy pregnancy, regardless of weight.
• Weight-loss diets are not recommended during pregnancy or immediately after childbirth. For tips on healthy eating, speak with a nutritionist.

Scientific review: Stéphanie Côté, M.Sc., nutritionist Research and copywriting:The Naître et grandir team Updated: April 2026

Photo : iStock.com/AtnoYdur