Pregnancy weight gain

It’s normal to experience changes in your body weight during pregnancy. Afterall, you’re growing another human being! There are many reasons for weight gain during pregnancy including the formation of the placenta and amniotic fluid, increased blood volume and storing of fat to prepare your body for breastfeeding after your baby is born. This article will explore pregnancy weight gain in more detail.

How much weight should you gain in pregnancy?

Average weight gain in pregnancy varies greatly and can depend on your pre-pregnancy weight and whether or not you have had children before. Most pregnant women gain between 10kg and 12.5kg (22lb to 26lb), with the majority of weight gain happening in the second trimester (after week 20)1.

Every person is different which is why there are no UK guidelines on how much weight you should gain during pregnancy. However, the Institute of Medicine (IOM) and National Research Council Recommendations (NRCR) are often used by midwives as a guide (see Table 1). 

Pregnancy weight gain chart

Table 1: A Guide to Weight Gain during Pregnancy²

What if I gain too much weight during pregnancy?

Gaining excess weight while you’re pregnant could lead to health problems for both you and your baby. Too much weight gain could cause you to have high blood pressure or may increase your risk of developing gestational diabetes (diabetes during pregnancy). Gestational diabetes can cause your baby to grow larger than usual and can result in premature birth or difficulties during delivery.

Pregnancy is not usually an appropriate time to go on a diet or attempt to lose weight. So it’s best to speak to your doctor or midwife if you are concerned about excess weight gain during pregnancy. A good way to look after yourself and your baby is to follow a healthy and balanced diet.

Find out what to eat when pregnant and what foods to avoid in pregnancy by joining the C&G baby club.

Being underweight while pregnant

If you are worried that you are not gaining enough weight while pregnant, try not to panic. The rise in human chorionic gonadotropin (hCG) (the hormone responsible for your positive pregnancy test) within the first trimester can cause nausea and even vomiting in some women, so it’s not uncommon to notice some initial pregnancy weight loss. It’s worth remembering that we are all different shapes and sizes, therefore it’s difficult to predict normal pregnancy weight gain. 

That said, gaining too little weight during pregnancy can cause complications for your baby including prematurity and low birth weight. If you’re worried about your weight gain during pregnancy, consider speaking with your doctor or dietitian as they can help you to make sure you’re getting enough nutrition to keep you and baby healthy.

Staying active

Some women might feel tired and naturally want to put their feet up, whilst others enjoy a good level of energy. Either way, staying active while you're pregnant can boost your mood and energy levels while preparing your body for the birth of your baby.

If you already take part in regular activity – keep it up (unless it's a contact sport or scuba diving). From dog walking to salsa dancing, there’s a better chance of sticking at exercise if you choose to do something you enjoy.

If you didn’t exercise before pregnancy, there are lots of things you can do to keep active. Start gradually, beginning with 15 minutes of exercise three times a week and increase slowly to 30-minute sessions over four or five days a week, eventually increasing to every day if you can.

Here’s a list of helpful hints to get active:

  • Climb the stairs instead of getting a lift
  • Take up an exercise class for some extra ‘you time’ - swimming, yoga, spinning or whatever works for you! 
  • Put some added energy into housework and gardening – it counts as exercise. 
  • Give your dog an extra walk - they’ll love it. 
  • Limit the time spent sitting down. Set that alarm and make sure you get up for a brisk walk or a stretch each hour.  

Read more about exercise during pregnancy here.

When will I get weighed during pregnancy?

During your pregnancy, you will be offered a range of tests, scans and appointments which are designed to keep you and your baby safe. At your first appointment with your midwife (known as the booking appointment) you will be weighed. Your height and weight are used to calculate your body mass index (BMI) as women with higher BMI can be at greater risk during pregnancy.

Some women find that being weighed during an appointment is stressful, distressing or upsetting, particularly when your body is undergoing such physical and hormonal changes. If you are worried about being weighed during pregnancy, discuss your feelings with your midwife.

Going forward, at each antenatal check your midwife will use a tape measure to measure the size of your bump. This will help to make sure your baby is growing well. Your midwife or GP may feel that you would benefit from specialist diet and exercise advice if you weigh:

  • More than 100kg (about 15.5 stone) 
  • Less than 50kg (about 8 stone) 

If at any point during your pregnancy you are worried about your weight or any other aspect of your health, ask your doctor or midwife for advice. To share your stories or to look for some friendly advice on pregnancy weight gain join the C&G baby club today.


Join the C&G baby club today

  • Weekly emails with tips and advice for your stage
  • 1-to-1 support from our dedicated Careline team, 8.30am - 5.30pm Monday to Friday.

Join the C&G baby club today

  • Weekly emails with tips and advice for your stage
  • 1-to-1 support from our dedicated Careline team, 8.30am - 5.30pm Monday to Friday.

Any more questions?

Our specialist baby advisors and experienced mums are here to talk and ready to help whenever you need them. You can call us or reach us on Live Chat 8.30am-5.30pm Monday-Friday.


Call 1800 570 570


For all the latest information

Email Us

Send us an email


8.30 am - 5.30pm Monday-Friday