Your pregnancy: A week by week fetal development guide

Having a baby is an amazing thing, and following your little one through their fetal development stages while you’re pregnant is fascinating.

There’s certainly lots to learn, so if you’re interested in how your mini-me is growing then we’ve put together a guide to show you exactly how your baby is changing during their nine months inside your tummy.

From the first few weeks of fetal development, when your baby is technically a ball of cells, through their transformation to an embryo and right up until your little one’s birth – this guide sees you through every week in confidence.

If you’re having twins, we’ve included information on how they will develop, too, and the changes you can make to help give your baby (or babies!) the best possible support while they grow.

You’ll learn all about how big your baby is growing during its fetal development stage, how much they weigh and all the things they’re learning, too. There are some surprises along the way (like how early they get finger nails!) and some useful information on scans, check ups and appointments.

Click on the image below, depending on what pregnancy week you’re currently in, to learn more…

Week by week fetal development guide

Week 1

Week 2

Week 3

Week 4

Week 5

Week 6

Week 7

Week 8

Week 9

Week 10

Week 11

Week 12

Week 13

Week 14

Week 15

Week 16

Week 17

Week 18

Week 19

Week 20

Week 21

Week 22

Week 23

Week 24

Week 25

Week 26

Week 27

Week 28

Week 29

Week 30

Week 31

Week 32

Week 33

Week 34

Week 35

Week 36

Week 37

Week 38

Week 39

Week 40

How far along are you? We love hearing all your pregnancy stories, so if you’re expecting then leave us a comment in the box below telling us how you’re feeling, what stage you’re at and any tips you’ve got for fellow mums-to-be!