Healthy weight gain during pregnancy

It is normal to gain weight during your pregnancy. This is due to the growth of the baby and placenta (afterbirth).

A healthy weight gain helps your womb, placenta and baby to grow. But you should avoid gaining too much weight during pregnancy.

If you are a healthy weight before you become pregnant, expect to gain 0.5kg per week in the second and third trimesters.

If you are underweight, you may need to gain more weight. If you are pregnant with more than one baby, such as a twin pregnancy, then you may also need to gain more weight.

If you are overweight, you may need to gain less. Discuss this with your midwife or GP.

Why healthy weight gain is important

You and your baby will both benefit if you maintain a healthy weight.

Benefits for your baby of a healthy weight gain

  • Supply of oxygen and nutrients.
  • Lower risk of complications at birth.
  • More likely to be born at a healthy weight.
  • Less risk of medical problems such as diabetes in later life.

Benefits of a healthy weight gain for you

  • You will feel healthier and have more energy.
  • You will be a healthier weight after your baby is born.
  • Reduced risk of complications during pregnancy and birth.
  • It helps to prepare your body for breastfeeding.

Calories and dieting during pregnancy

Most women do not need extra calories during the first trimester of pregnancy.

Most women will need around 250 extra calories in the second trimester, and up to 500 extra calories in the third trimester.

Most weight gain happens in the second and third trimester. A healthy weight gain depends on how much you weighed before you became pregnant.

Do not try to lose weight by going on a diet. Instead, focus on healthy eating and staying active.

Extra food servings

In the second and third trimester you can include an extra 2 to 3 servings a day of nourishing foods from the food pyramid. This is to allow for the slight increase in energy and nutrients you need.

This could include:

  • a serving of fruit
  • baked beans
  • a glass of milk
  • 20g of almonds
  • a slice of bread
  • a tin of salmon
  • 125g of yoghurt
  • 2 rye crackers with light cheese

If you are underweight

Being underweight increases the chances of a premature birth for your baby. It also increases the chances of your baby having a low weight at birth.

You may also be at risk of some nutrient deficiencies.

In this case, you may need to gain more weight to:

  • bring you to a healthy weight
  • make sure you are getting the nutrition you and your baby need during pregnancy

Your midwife or GP will check your weight. They will tell you how much weight you should gain for a healthy pregnancy.

If you are overweight or obese

If you are overwight or have obesity, you have a greater risk of developing gestational diabetes. You are also at a greater risk of high blood pressure during pregnancy.

There are also some risks to your baby. These include an excessive birth weight, or being born with low blood sugar or breathing problems.

Losing weight is not recommended when you are pregnant.

If you're worried that you are overweight or have obesity:

  • talk to your GP, midwife or obstetrician about ways to reduce the risk to you and your baby - they may refer you to a dietitian
  • make healthy changes to what you eat
  • stay physically active
  • talk with your obstetrician or midwife about the safest way, and place, for you to give birth

Foods to avoid in pregnancy

Healthy eating during pregnancy

Page last reviewed: 30 September 2022
Next review due: 30 September 2025