Pregnancy Weight Gain: All You Need to Know

During pregnancy, it’s perfectly normal and healthy to gain a few extra kilos of weight. We can’t tell you exactly how much weight is normal and healthy to gain during pregnancy – this depends on factors like your starting weight and whether you’re having a single baby or multiples.

We can, however, tell you how to achieve healthy weight gain in pregnancy, what makes up those extra kilograms you’re gaining, and how many extra calories you may need now that you’re pregnant. Scroll down to find out more.

How Much Weight Should You Gain During Pregnancy?

It’s very common for people to wonder how much weight to gain in pregnancy. The average weight gained during pregnancy is 10 to 12.5 kg; however, no two pregnant people are the same, which is why the average recommended weight gain in pregnancy will mostly depend on whether you had a normal weight, or were underweight or overweight, before you became pregnant. This is determined by your pre-pregnancy BMI.

The general rule of thumb is that if you have a low BMI, then your recommended weight gain will be more than for someone with a higher BMI. If you’re uncertain about what’s right for you, talk to your doctor or midwife about the healthy amount of weight for you to gain during your pregnancy.

What Is BMI?

BMI is short for body mass index, which is a ratio derived by calculating your weight (in kilograms) divided by your height (in metres), squared. It offers an estimate for measuring body fat.

Search online for a BMI calculator or chart to help you find your pre-pregnancy result and use it – along with the chart below – to find out what’s a healthy average pregnancy weight gain for someone of your build and height.

What if You’re Pregnant With Twins?

If you’re pregnant with twins or triplets, you might gain a bit more weight than a pregnant person who’s carrying a single baby. This is perfectly normal.

You don’t need to eat much more though. In fact, the advice from experts is more or less the same whether you’re pregnant with one or more babies. That is, avoid sugary drinks and snacks and stick to a healthy diet that includes

• plenty of fruit, vegetables and whole grains

• some high-protein foods like lean red meat, nuts, seeds and (well-cooked) eggs

• dairy foods like milk, cheese and yoghurt (or dairy substitutes).

If you’re pregnant with multiples, you might have a slightly higher risk of anaemia (iron deficiency), so your doctor may offer you iron supplements. You can also try and boost your iron intake by eating more foods that are rich in this mineral, such as lean red meat, leafy green vegetables, beans and iron-fortified breakfast cereals.

Where Does the Weight Gain in Pregnancy Come From?

Typically, only a small portion of the weight you gain in pregnancy is actually fat. The average weight gained during pregnancy is 10 to 12.5 kg. Here is a breakdown of what that’s made up of:

• Your baby (around 3-3.5 kg)

• Uterus (around 1kg)

• Amniotic fluid (around 1kg)

• Placenta (around 700 g)

• Larger breasts (around 2kg)

• Increased blood and fluid volume (up to 2kg)

• Extra fat stores (around 3kg).

Why Do You Gain Weight During Pregnancy?

Much of the extra weight you normally gain during pregnancy is to provide your growing foetus with the nourishment and protection they need to develop and grow inside your uterus.

The extra blood and fluid circulating around your body, for example, is needed to carry oxygen and nutrients to your little one via the placenta (which itself adds around a kilogram to your weight while you’re pregnant).

The amniotic fluid helps keep your foetus at the right temperature and cushions them from any knocks or bumps.

In fact, most of this extra weight amounts to a complete life support system for your little one – how amazing is that?

Of course, you’ll lose most of the weight you gained in pregnancy when your baby is born, but you will still need those extra fat stores to fuel breast milk production.

Recommended Weight Gain During Pregnancy

To help promote a healthy, gradual pregnancy weight gain during each trimester, you and your midwife or doctor may rely on the following guidelines:

• First trimester. During the early weeks of pregnancy in the first trimester, it’s likely you won’t be gaining any extra weight, but you may notice some bloating around your stomach. It’s also possible to lose weight during these first few months, especially if you’re dealing with morning sickness. You don’t necessarily need to include any extra calories in your diet during your first trimester of pregnancy.

• Second and third trimesters. Not all pregnant people need to add extra calories, but your midwife or doctor may recommend including an extra 200 calories a day in your third trimester of pregnancy. With your baby growing steadily, it’s possible to gain between 0.4 and 0.5 kilograms each week if you started your pregnancy at a healthy weight.

The guidelines may vary depending on your BMI and other factors, such as if you’re expecting twins or multiples. It’s always best to talk to your midwife or doctor before adjusting your diet during pregnancy.

Pregnancy Weight Gain Chart

To get an idea of what’s considered to be normal weight gain in pregnancy, first work out your starting BMI (before pregnancy) (or use an online calculator) and check it against our pregnancy weight gain chart below to find your approximate recommended weight gain during pregnancy.

If your weight isn’t in the normal range, don’t panic: Your midwife can advise you on how to maintain a healthy diet.

Most pregnant people who are above the average weight range for their BMI, will give birth to a healthy baby. However, being overweight can increase the risk of complications during your pregnancy, including gestational diabetes or the rare but serious blood pressure condition preeclampsia.

Dieting to lose weight during pregnancy is not safe for your foetus, but you may be able to lower the risks by switching to a healthier diet or taking steps not to gain any more weight than necessary.

Attending all your antenatal appointments is a good way of ensuring that any problems are spotted and dealt with in good time, as your weight will be monitored at these visits.

If you have a BMI of more than 30, your midwife may recommend a different schedule of antenatal care, with extra tests and monitoring to manage the higher risks.

Pregnancy Weight Gain: Week by Week

A steady increase in weight throughout your pregnancy is beneficial, and keeping an eye on your weight gain week by week within each trimester can give you a broad idea of your progress. This article offers guidance on what’s the average weight gain during a healthy pregnancy, if you're expecting one baby and starting from a usual BMI. If your pre-pregnancy BMI is lower or higher than average, or if you’re expecting twins or more, consult your midwife or doctor concerning the optimal weight gain for you. This guide is primarily for your general understanding.

Pregnancy Weight Gain: First Trimester

The first trimester typically encompasses weeks 1 to 12. Bear in mind that in these early stages of pregnancy, you probably won’t gain much weight. So, how much weight do you gain in early pregnancy? It varies from person to person. However, for an average pregnancy, you might gain up to 0.5 kilograms (five pounds) in the first three months, despite the possibility of weight loss during this first period.

• Weeks 1 to 4. In your first month of pregnancy, you might not even be aware that you’re expecting! You might not experience any symptoms or observe any weight gain. This has to do with how your pregnancy weeks are dated from the first day of your last menstrual period.

  • If your pregnancy starts at the beginning of your last menstrual cycle, then ovulation (and thus conception) doesn’t usually occur until 14 days or more into the cycle (assuming you have a 28-day cycle).

  • Given that technically you’re not pregnant until about week 3, it’s rare to see any weight gain during your first month of pregnancy.

• Weeks 5 to 8. Although your body may be experiencing significant changes during these weeks, you still might not gain much weight. In fact, if you’re dealing with morning sickness, it’s possible to lose some weight during this time.

  • Hormonal changes might lead to digestive problems, causing nausea, vomiting or specific food aversions.

  • However, these same hormones could make your breasts enlarge as milk-producing glands expand, which could contribute to a slight weight gain.

• Weeks 9 to 12. If you do see any weight gain in early pregnancy, it will likely happen during these weeks as morning sickness and other digestive issues may start to decrease.

  • Your breasts will continue to enlarge due to the growth of milk-producing glands, so they may feel fuller or heavier.

  • You could gain a little weight, due to growing breasts, placenta and uterus, augmented by increased volumes of amniotic fluid and blood.

Pregnancy Weight Gain: Second Trimester

When do you truly start gaining weight in your pregnancy? During your second trimester, which typically includes weeks 13 to 27, is when you might begin to see that gradual weight gain. Generally, pregnant people gain the majority of their pregnancy weight after week 20. As mentioned above, talk to your midwife or doctor about whether you need to increase your daily calorie intake.

• Weeks 13 to 17. You may start to gain a little bit of weight over this period. It’s not unusual to see more weight gain one week compared to another.

• Weeks 18 to 22. During these weeks, it’s possible to notice some weight gain and your baby bump expanding. In particular, you might notice your breasts have grown one or two cup sizes.

• Weeks 23 to 27. Your baby’s development is starting to impact your weight gain, as your little one continues to grow and gain fat under their skin!

Pregnancy Weight Gain: Third Trimester

The third trimester typically consists of weeks 28 to 40 and beyond. At this point in your pregnancy, your weight gain may start to look fairly consistent at around 0.5 kilograms per week. So, how much weight do you gain in the third trimester of pregnancy and what’s a healthy range? Keep in mind that healthy weight gain in pregnancy is different for each person.

• Weeks 28 to 31. As you settle into your third trimester of pregnancy, you might start to gain weight more consistently – at a rate of about 0.5 kilograms each week.

  • This weight probably won’t include fat, though. Instead, weight gain in these weeks of pregnancy is usually from your developing baby, growing placenta and increased fluids (amniotic and body tissue fluids).

  • Weight gain could also cause aches and pain or other sensations, like swollen hands and feet.

• Weeks 32 to 35. You’re in the home stretch of your pregnancy, and you may gain about 450 grams a week. You don’t want to gain too much during these final weeks, especially if you had a higher pre-pregnancy BMI. Continue to work with your midwife or doctor and keep an eye on your weight.

• Weeks 36 to 40. During your final weeks of pregnancy, your baby is nearly fully developed. This means that you might not notice as much weight gain.

How to Maintain a Healthy Weight During Pregnancy

Everyone is different, so that means your pregnancy weight gain will be specific to you. Your pre-pregnancy BMI will impact how much weight you are advised to gain, as will other factors. Here are some general tips for maintaining a healthy weight during pregnancy.

• Enjoy a healthy, balanced diet. Do not diet while you’re pregnant but be mindful of the foods you consume. Make sure you eat a variety of nutritious, healthy food like fruits, vegetables, proteins, wholegrain or high-fibre carbohydrates and dairy products, focusing on foods that offer a range of vitamins and minerals. Maintaining a balanced diet during pregnancy is important to your health and the health of your baby. Essential nutrients for your pregnancy include vitamins A, B, C and D, plus calcium and iron, and, of course, folic acid.

• Plan your meals. When you’re dealing with cravings, aches and pains or morning sickness, it can be extra challenging to prepare healthy choices on the spot. Instead, spend some time planning and preparing meals and snacks ahead of time. Ask your partner, family or friends to help!

• Resist eating for two. Resist the temptation to ‘eat for two’. You definitely don’t need to indulge in double portions of chocolate and ice cream to nourish your growing baby. On average, your calorie needs during pregnancy may only be an extra 200 calories each day in your third trimester. Your GP or midwife can help you follow a healthy pregnancy nutrition plan and give you advice on a target weight based on your starting weight.

• Get moving and stay active. Staying active with gentle exercise is also beneficial – in more ways than one. For example, besides helping to keep your weight gain under control (by using up any unneeded calories), it also tones the muscles and helps prevent aches and pains caused by the extra kilos you put on during pregnancy, as well as helping to prepare your body for labour and birth. Activities that are easy on the joints are best, like swimming or prenatal yoga.

If you have food intolerances or follow a special diet, your doctor will be able to help you tailor your diet to ensure you’re getting the nutrients you need. In some cases, your doctor may recommend you take extra prenatal vitamins if you’re not getting enough of certain vitamins or minerals through diet alone.

If you’re overweight or underweight, your midwife may give you some extra nutrition advice so both you and your little one stay healthy throughout the duration of your pregnancy.

By the way, there are some foods you should avoid eating while pregnant, so read up on them too!

The Bottom Line

The most important thing during your pregnancy is your health and that of your baby. Here are a few things to remember when it comes to pregnancy weight gain:

• Everyone is different. Most pregnancy weight gain guides are general because every pregnancy is different. Our resources function as a foundation and guide but talk with your midwife or doctor to understand your individual pregnancy weight goals.

• Weight gain should be gradual. Above all else, your pregnancy weight gain should be gradual and somewhat consistent. If it’s not, it’s best to consult your midwife or doctor. This means you can focus less on how much you might be gaining at one time and more on your pregnancy as a whole.

• Consider your BMI. Although BMI isn’t the best indicator of overall health, it’s helpful when determining your ideal pregnancy weight gain.

• Enjoy a balanced diet and gentle exercise. Help maintain a healthy pregnancy weight with a balanced diet and light exercise.

• Talk to your midwife or doctor. Pregnancy is a long journey, and your midwife and doctor are your best source of support, advice and guidance for your unique situation.

_{How we wrote this article The information in this article is based on the expert advice found in trusted medical and government sources, such as the National Health Service (NHS). You can find a full list of sources used for this article below. The content on this page should not replace professional medical advice. Always consult medical professionals for full diagnosis and treatment.}