September 28, 2026

Pregnancy weight gain: how much is normal by BMI

Q: How much weight do you gain in a normal pregnancy?

It depends on your starting BMI: 11.5 to 16 kg if you started at a normal weight, 12.5 to 18 kg if you were underweight, and less if you started from overweight or obesity. The calculator above gives you your own range.

Calculadora de aumento de peso en el embarazo

Introduce tu peso y tu altura antes del embarazo

Tu peso antes del embarazo

Tu altura

“How much weight should I gain?” is one of the questions I get asked most – and the honest short answer is: it depends on your BMI before pregnancy. There’s no single number that fits everyone, and comparing yourself to a friend, your sister or something you saw on social media is the fastest route to unnecessary worry. So let’s put some real numbers on it: the weight gain calculator above gives you your recommended range in seconds, and here I’ll explain how that gain is spread across the nine months ❤️.

Pastel watercolour illustration of a kitchen scale, a symbol of weight tracking

How much weight should you gain during pregnancy?

Your recommended gain is worked out from your BMI (body mass index) before you conceived, not from the weight you’re carrying today. BMI is your weight in kilos divided by your height in metres squared:

BMI = weight (kg) / height (m)²

For example, if you weighed 60 kg and you’re 1.65 m tall: 60 / (1.65 × 1.65) = 22.0, which is a normal weight. That figure is what sets your range, because your starting point determines how much you can reasonably afford to put on.

These ranges are for a pregnancy with one baby. If you’re expecting twins, the recommendation is different and wider – ask your medical team what applies to you.

Pregnancy weight gain chart by BMI

This is the reference most commonly used in antenatal appointments. Treat it as a range rather than a target: staying a little above or a little below it is still normal.

Pre-pregnancy BMI	Category	Recommended total gain	Rate in the 2nd and 3rd trimester
Under 18.5	Underweight	12.5 to 18 kg	0.44 to 0.58 kg per week
18.5 to 24.9	Normal weight	11.5 to 16 kg	0.35 to 0.50 kg per week
25 to 29.9	Overweight	7 to 11.5 kg	0.23 to 0.33 kg per week
30 or over	Obesity	5 to 9 kg	0.17 to 0.27 kg per week

If your numbers land between two categories, don’t obsess over decimals. What actually matters is the trend across your pregnancy, not the scales on any single day – weight fluctuates with fluid retention, digestion and even what you’re wearing.

Pregnancy weight gain by trimester

First trimester (weeks 1 to 13)

It’s normal to gain very little here: between 0.5 and 2 kg in total, and it’s fine to lose a bit in the early weeks. Morning sickness, food aversions and a changed appetite mean plenty of women don’t gain anything at all until the second trimester. If that’s you and your midwife is happy with how things are going, there’s nothing to worry about.

Second trimester (weeks 14 to 27)

This is when steady gain kicks in. It’s the stage where the weekly rate in the chart is easiest to follow: roughly 0.3 to 0.5 kg per week if you started at a normal weight. Your bump grows, your baby puts on weight and your body starts laying down reserves for breastfeeding.

Third trimester (week 28 to birth)

You keep gaining, although some women plateau or even drop slightly in the final weeks because there’s simply less room for food. Remember your baby is still growing: most of a newborn’s weight is gained in these last weeks, so this is not the time to cut back.

What makes up the weight you gain

This one helps a lot with any guilt you might be feeling: your baby isn’t even half of what you put on. A gain of around 12 kg breaks down roughly like this:

Baby: 3 to 3.5 kg
Placenta: 0.5 to 1 kg
Amniotic fluid: around 1 kg
Uterus and breasts: 1.5 to 2 kg
Extra blood volume: 1.5 to 2 kg
Retained fluid: 1.5 to 2 kg
Fat stores (for breastfeeding): 2.5 to 4 kg

In other words, a big chunk of that weight disappears within the first weeks after birth. What lingers is the fat reserve – which is exactly what your body needs to make milk.

When to talk to your midwife or doctor

Don’t panic over one odd week, but do get in touch if:

You gain more than 1 kg in a week repeatedly, especially alongside sudden swelling of your hands and face, a severe headache or blurred vision. Those signs can be linked to pre-eclampsia and need assessing the same day.
You lose weight after the first trimester, or don’t gain anything for several weeks in a row.
You’re dieting on your own to avoid gaining. Restricting food in pregnancy is never the answer – if your weight worries you, that’s a conversation for your midwife, not for a diet app.
The scales are making you anxious. That’s a legitimate thing to feel and your midwife can help.

If anything is on your mind, contact your midwife rather than waiting for your next appointment. There’s no such thing as a silly question when it’s your pregnancy.

Tips for healthy pregnancy weight gain

Eat a varied diet without counting calories. Portion size and quality matter far more than arithmetic. You only need about 300-450 extra calories a day in the third trimester – much less than most people think.
Split it into 5-6 smaller meals. It helps with sickness, heartburn and sudden hunger.
Prioritise protein, fibre and healthy fats: pulses, eggs, fish, fruit, vegetables, nuts and olive oil.
Move every day: walking, swimming or prenatal yoga. Gentle, adapted exercise helps manage weight gain and can make labour easier.
Weigh yourself once a week at most, at the same time of day and in the same clothes. Daily weighing just creates noise.
Don’t compare yourself to anyone else. Two pregnancies in the same woman can follow completely different patterns. If you want a sensible benchmark, have a look at how pregnancy develops week by week.
If you haven’t confirmed your pregnancy yet and want a sense of your symptoms, you can take our free online pregnancy test. And if you fancy a bit of fun, try our finger pregnancy test game: it’s only a game, not a real test.

FAQ

How much weight do you gain in a normal pregnancy? It depends on your starting BMI: 11.5 to 16 kg if you started at a normal weight, 12.5 to 18 kg if you were underweight, and less if you started from overweight or obesity. The calculator above gives you your own range.

Is it bad to go over the recommended range? Going slightly over isn’t a disaster, but staying well above it is linked to a higher risk of gestational diabetes, high blood pressure and more complicated births, for you and your baby. The answer is to discuss it at your appointment and adjust your habits – never to start dieting on your own.

Can I diet so I don’t gain as much? Not during pregnancy. Cutting calories yourself can affect your baby’s development. If your diet needs adjusting, that’s something to do with a professional.

Why am I gaining more than the chart says when I eat normally? Fluid retention, metabolism, genetics and how active you were before all play a part. It’s a guide, not an exam. Your midwife looks at the whole picture: weight, blood pressure, blood tests and your baby’s growth.

Does all the weight come off after birth? A good part of it does. Labour takes care of the baby, placenta and amniotic fluid (around 5-6 kg), and the rest of the fluid follows in the weeks after. Getting back to your pre-pregnancy weight usually takes months and shouldn’t be rushed – with breastfeeding and healthy habits it tends to happen on its own.

What if I’m expecting twins? The ranges are wider (generally 17 to 25 kg if you started at a normal weight, though this varies between guidelines and individual cases). Always check with your medical team, because twin pregnancies are monitored more closely.

Sources

This article is for information only and doesn’t replace the advice of your doctor or midwife. If you have any concerns about your pregnancy, always speak to a healthcare professional ❤️.