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Weight gain in pregnancy

During pregnancy, weight gain causes your appearance to change. Find out about the average weight gain in pregnancy and how much you are likely to put on.

Weight gain in pregnancy will cause your body to change in size and shape as your bump and baby grow. In the UK, there is no guidance on how much weight you should gain, and at what rate you will gain it. It is also recognised that individual weight gain can vary, without this being an indication of a problem.

This article covers average weight gain in pregnancy, what your body mass index is, eating habits, feelings about looking pregnant and other changes in your body.

Average weight gain in pregnancy

Depending on your weight to begin with, most women will gain between 18 and 30 pounds on average, with most of that weight gain after week 20.

Most of the extra weight is due to your growing baby, but the following will also contribute to weight gain during pregnancy:

  • the placenta,
  • membranes and amniotic fluid,
  • extra fluid retained throughout the body,
  • increase in blood supply,
  • your uterus,
  • energy stored in the form of fat (often more noticeable on hips, thighs, face or arms) and
  • your growing breasts (see below).

You may expect to gain around four pounds in the first trimester and then up to a pound a week for the next six months, but this varies greatly.

What is my body mass index?

Your body mass index (BMI) measures your weight in relation to your height. At your first antenatal appointment (your booking appointment, your midwife will calculate your BMI. The amount of weight that you might put on in pregnancy depends on what your BMI was before you were pregnant.

A high or low BMI will be referred to a consultant following the booking appointment. Women with a BMI of more than 30 before pregnancy may be offered a weight management programme during pregnancy, as this has been shown to keep them healthy, and make labour and birth more straightforward.

Not eating for two

‘Eating for two’ is a myth. There’s actually no need to eat any more than you usually would. Instead continue to eat healthily, according to your appetite. There is also no need to increase your calorie intake until the final three months of your pregnancy, and even then it should only be increased by about 200 calories a day, but most women will simply adjust their intake unconsciously, to accommodate this.

Looking pregnant

When you start ‘looking pregnant’ can vary a great deal. Ask other mums about their experiences and you will find some women noticed a slight difference in shape in the early weeks, whereas others didn’t notice any changes until about four months.

By four to five months, almost all women will find their waistbands are uncomfortable, and their breasts are larger than before. A definite ‘pregnancy bump’ might also be noticeable - though loose clothing may well hide it to a casual observer.

Other changes in your body

Your breasts will start to prepare for breastfeeding from the very first weeks of pregnancy, and this usually makes them larger than before. Your nipples may darken in colour and the areola (the coloured skin area surrounding the nipples) may also darken and spread a little, due to the extra melanin (a group of natural pigments), which is produced when you are pregnant.

As well as affecting skin pigmentation, melanin can also sometimes affect your abdomen (it produces a vertical line, called the linea nigra), your face and patches elsewhere on your body.

What if you don’t like the way your body looks in pregnancy?

While some women embrace the changes in their body, seeing it as a sign of their baby growing, others may have negative feelings about their changing body shape. Dissatisfaction with the way you look when you are pregnant is very common, especially so in the second three months, according to some research. This is sometimes linked to previous body image feelings – if you already feel self-conscious or self-critical about your body - being pregnant is unlikely to make these feelings suddenly go away. However, other research shows that some women find being pregnant gives them a chance to feel less pressured – no one expects a pregnant woman to be slim, after all.

For some women, shyness and self-consciousness about their body can have an impact on their feelings about labour and birth. The thought of others seeing their body during labour is unwelcome and even frightening. Read our article about fear of childbirth for more information.

Women who have a history of eating disorders are shown in research to have a particularly high risk of concern about their body in pregnancy. Poor body image is taken more seriously than it used to be, as it can be a risk factor in the development of depression and other mental and emotional health issues.

If you are finding the body changes difficult to cope with, and if you are experiencing your feelings more intensely, then do speak to your midwife. She can help you decide if this is something that can be helped by counselling, or just a sympathetic ear and emotional support from your partner, family or a good friend.

Further information

NCT's helpline offers practical and emotional support with all aspects of being pregnant, birth and early parenthood: 0300 330 0700. We also offer antenatal courses which are a great way to find out more about birth, labour and life with a new baby.

You might find this factsheet useful: Information about weight gain when you are pregnant What obstetricians say: 'Why your weight matters when you are pregnant and after birth'

Visit the Healthy Start website for recipes, more on healthy eating and how you can claim the vouchers.