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How big is my baby? Baby size by week
3 weeks pregnant: a grain of sherbet
At three weeks pregnant, your fertilised egg or blastocyst is the size of a grain of sherbet.
It's difficult to measure your baby's exact length and weight at this stage as they are still so tiny!
Read about your baby's development at 3 weeks pregnant.
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4 weeks pregnant: a grain of sugar
At four weeks pregnant, your fertilised egg or zygote is the size of a grain of sugar.
It's still difficult to measure your baby's exact weight and length just yet!
Read about your baby's development at 4 weeks pregnant.
5 weeks pregnant: a cake sprinkle
At five weeks pregnant, your baby is the size of a cake sprinkle.
Length (crown to rump): your baby will double in length this week, from from 2mm to 4mm.
Weight: It's difficult to measure an exact weight for your baby until they reach around eight weeks. They're still so little!
6 weeks pregnant: a Millions sweet
At six weeks pregnant, your baby is the size of a Millions sweet.
Length (crown to rump): 4 to 7mm.
Weight: Your baby still weighs below one gram, so it's difficult to weigh them just yet!
7 weeks pregnant: a Smartie
At seven weeks pregnant, your baby is the size of a Smartie.
Length (crown to rump): around 1cm.
Weight: Your baby won't reach 1g until next week. They're still tiny!
8 weeks pregnant: a Malteser
At eight weeks pregnant, your baby is the size of a Malteser.
Length (crown to rump): 1.6cm.
Weight: by eight weeks, your baby will weigh just 1 gram.
9 weeks pregnant: a Galaxy Minstrel
At nine weeks pregnant, your baby is the size of a Galaxy Minstrel.
Length (crown to rump): 23mm
Weight: 2g
10 weeks pregnant: a giant chocolate button
At ten weeks pregnant, your baby is the size of a giant chocolate button.
Length (crown to rump): 3.1cm.
Weight: 3 to 4g.
11 weeks pregnant: a macaron
At 11 weeks pregnant, your baby is the size of a macaron.
Length (crown to rump): 4cm.
Weight: around 7g.
12 weeks pregnant: a Freddo bar
At 12 weeks pregnant, your baby is the size of a Freddo bar.
Length (crown to rump): 5.4cm.
Weight: 14g.
13 weeks pregnant: Lindt chocolate bunny
At 13 weeks pregnant, your baby is the size of a Lindt chocolate bunny.
Length (crown to rump): 7.4cm.
Weight: 23g.
14 weeks pregnant: a Terry's Chocolate Orange
At 14 weeks pregnant, your baby is the size of a Terry's Chocolate Orange.
Length (crown to rump): 8.7cm.
Weight: 43g.
15 weeks pregnant: a toffee apple
At 15 weeks pregnant, your baby is the size of a toffee apple.
Length (crown to rump): 10cm.
Weight: 70g.
16 weeks pregnant: a Fudge bar
At 16 weeks pregnant, your baby is the length of a Cadbury Fudge bar.
Length (crown to rump): 11.5cm.
Weight: 100g.
17 weeks pregnant: a chocolate eclair
At 17 weeks pregnant, your baby is the length of a chocolate eclair.
Length (crown to rump): 13cm.
Weight: 140g.
18 weeks pregnant: a doughnut
At 18 weeks pregnant, your baby is the size of a doughnut.
Length (crown to rump): 14cm.
Weight: 190g.
19 weeks pregnant: a Curly Wurly
At 19 weeks pregnant, your baby is the length of a Cadbury Curly Wurly bar.
Length (crown to rump): 15cm.
Weight: 240g.
20 weeks pregnant: a pack of Digestive biscuits
At 20 weeks pregnant, your baby is the length of a pack of Digestive biscuits.
Length (crown to heel): 25.6cm. This might see like a big jump, as your baby is now measured from crown to heel, rather than crown to rump.
Weight: 300g.
21 weeks pregnant: a tub of Häagen-Dazs
At 21 weeks pregnant, your baby is the size of a tub of Häagen-Dazs ice cream.
Length (crown to heel): 26.7cm.
Weight: 360g.
22 weeks pregnant: a box of Cadbury Heroes
At 22 weeks pregnant, your baby is the size of a medium box of Cadbury Heroes.
Length (crown to heel): 27.8cm.
Weight: 430g.
23 weeks pregnant: a sharing bag of marshmallows
At 23 weeks pregnant, your baby is the size of a sharing bag of marshmallows.
Length (crown to heel): 28.9cm.
Weight: 501g (almost a whole pound).
24 weeks pregnant: a large Toblerone
At 24 weeks pregnant, your baby is the length of a large Toblerone.
Length (crown to heel): 30cm.
Weight: 600g.
25 weeks pregnant: a tub of Kelly's ice cream
At 25 weeks pregnant, your baby is the size of a tub of Kelly's ice cream.
Length (crown to heel): 34.6cm.
Weight: 660g.
26 weeks pregnant: a sharing Yule log
At 26 weeks pregnant, your baby is the size of a sharing Yule log.
Length (crown to heel): 35.6cm.
Weight: 760g.
27 weeks pregnant: a 2 litre bottle of fizzy drink
At 27 weeks pregnant, your baby is the length of a 2 litre bottle of fizzy drink.
Length (crown to heel): 36.6cm.
Weight: 875g.
28 weeks pregnant: a birthday cake
At 28 weeks pregnant, your baby is the size of a birthday cake.
Length (crown to heel): 37cm.
Weight: around 1kg.
29 weeks pregnant: a 1kg jar of pick 'n' mix
At 29 weeks pregnant, your baby's weight is just over that of a 1kg jar of pick 'n' mix.
Length (crown to heel): 15.7 inches.
Weight: 1.2kg.
30 weeks pregnant: a large apple pie
At 30 weeks pregnant, your baby is the size of a large apple pie.
Length (crown to heel): 39.9cm.
Weight: 1.31kg.
31 weeks pregnant: a giant Easter egg
At 31 weeks pregnant, your baby is the size of a giant Easter egg.
Length (crown to heel): 41cm.
Weight: 1.5kg.
32 weeks pregnant: a dozen cupcakes
At 32 weeks pregnant, your baby is around the size of a dozen cupcakes.
Length (crown to heel): 42cm.
Weight: 1.7kg (they've put on 200-250g in the past week alone!).
33 weeks pregnant: a tub of Celebrations
At 33 weeks pregnant, your baby is the size of a tub of Celebrations.
Length (crown to heel): 43cm.
Weight: 1.9kg.
34 weeks pregnant: a 2kg jar of pick 'n' mix
At 34 weeks pregnant, your baby weighs as much as a 2kg jar of pick 'n' mix.
Length (crown to heel): 45cm.
Weight: 2.1kg.
35 weeks pregnant: a large stick of candyfloss
At 35 weeks pregnant, your baby is the size of a large stick of candyfloss.
Length (crown to heel): 46.2cm.
Weight: 2.3kg.
36 weeks pregnant: a 2.5kg jar of boiled sweets
At 36 weeks pregnant, your baby weighs as much as a 2.5kg jar of boiled sweets.
Length (crown to heel): 47.4cm.
Weight: 2.6kg.
37 weeks pregnant: a tub of cinema popcorn
At 37 weeks pregnant, your baby is the size of a large tub of cinema popcorn.
Length (crown to heel): 48.6cm.
Weight: 2.95kg.
38 weeks pregnant: a dozen doughnuts
At 38 weeks pregnant, your baby is around the size of a dozen doughnuts.
Length (crown to heel): 49.8cm.
Weight: 3.1kg (that's nearly 7Ib!).
39 weeks pregnant: a traybake cake
At 39 weeks pregnant, your baby is the size of a traybake cake.
Length (crown to heel): 50.7cm.
Weight: 3.28kg.
40 weeks pregnant: a small wedding cake
At 40 weeks pregnant, your baby is the size of a small wedding cake.
Length (crown to heel): 50cm (the average birth length for a baby in the UK).
Weight: 3.5kg, around 7lb 11oz, (the average birthweight for a baby in the UK).
41 weeks pregnant: a small wedding cake
At 41 weeks pregnant, your baby is the size of a small wedding cake - and they won't have changed much since last week.
Length (crown to heel): around 50cm.
Weight: 3.5kg (7lb 11oz).
Can you believe that in the space of just 40 weeks your baby will grow from the size of a grain of sherbet to a full wedding cake? Amazing, right?
As you move through your pregnancy , your little one will be growing and developing every single day, from their little limbs first developing, to growing hair inside the womb!
To help you visualise the exact size, length and weight of your baby each week, we've created this handy guide which will tell you exactly how your baby measures up to your favourite sweet treats each week - whether they're a little Freddo bar or a full tub of popcorn!
So, click through the gallery to watch your baby grow - and keep this page handy if you want to check back as you progress through your pregnancy. Plus, click the article link on each slide to find out more about how your baby's developing this week, and what you need to be prepared for.
Now... anyone for a snack?
What to Expect When You're Expecting by Heidi Murkoff is a must-read for all expectant parents. See more details here at Amazon.
You can also buy it here at Waterstones.
Are you looking for more information on what to expect throughout your pregnancy? Check out our articles below or chat to other parents in the Netmums forum...