Pregnancy Week by Week
Our week by week pregnancy guide provides expectant parents with everything they need to know about baby's growth and development, including medically-accurate illustrations of fetal development, information about the changes going on for mum and baby, and even tips and fun facts! Click on one of the weeks below to get started.
You may be confused about how many weeks are in each trimester, and when each trimester starts and ends. There are actually several different methods to calculating the dates of trimesters, which is why you may see different websites list 12 or 13 weeks as the end of the first trimester. We use the gestation method, which counts the 40 weeks of gestation starting with the first day of your last period. The other popular approach is the baby development method which ignores the two weeks pre-conception and therefore is a 38 week cycle where the second trimester starts at week 12.
First Trimester
Pregnancy Week 1
Preparing for conception
Pregnancy Week 2
Ovulation
Pregnancy Week 3
Egg fertilisation happens
Pregnancy Week 4
Baby is growing inside you
Pregnancy Week 5
Baby looks like a tadpole
Pregnancy Week 6
Baby is size of a sesame seed
Pregnancy Week 7
Baby's brain develops
Pregnancy Week 8
Baby's hands appear
Pregnancy Week 9
Baby responds to touch
Pregnancy Week 10
Tongue is fully formed
Pregnancy Week 11
Fingernails and hair appear
Pregnancy Week 12
Baby can open it's mouth
Pregnancy Week 13
Vocal cords form
The first trimester starts on the date of your last period before conception, and lasts until the baby has been growing and developing for 11 weeks. During this time, they will grow from less than the thickness of a human hair to the size of a plum!
Second Trimester
Pregnancy Week 14
Baby practices using its lungs
Pregnancy Week 15
Baby can make a fist
Pregnancy Week 16
Baby reaches 100g in weight
Pregnancy Week 17
Baby practices blinking
Pregnancy Week 18
Bones begin to harden
Pregnancy Week 19
Baby can hiccup!
Pregnancy Week 20
Baby sleeps and wakes
Pregnancy Week 21
Halfway there!
Pregnancy Week 22
Baby responds to outside noise
Pregnancy Week 23
Downy hair covers baby's body
Pregnancy Week 24
You can hear baby's heartbeat
Pregnancy Week 25
Baby may suck its thumb
Pregnancy Week 26
Eyebrows and eyelashes appear
If you found your first trimester hard going, be assured that for many expectant mums, the second trimester is often nicknamed the 'honeymoon period'. As your baby grows to the size of a cauliflower you should focus on preparing for their arrival and making sure they're getting the nutrients they need!
Third Trimester
Pregnancy Week 27
Lungs capable of breathing air
Pregnancy Week 28
Baby's eyelids open
Pregnancy Week 29
Eyes prepare to see
Pregnancy Week 30
Brain develops rapidly
Pregnancy Week 31
Baby's growth begins to slow
Pregnancy Week 32
Baby can use all 5 senses
Pregnancy Week 33
Skin changes colour
Pregnancy Week 34
Baby's eyes are blue
Pregnancy Week 35
Baby preparing for birth
Pregnancy Week 36
Finishing period
Pregnancy Week 37
Baby turns towards light
Pregnancy Week 38
Toenails reach end of toes
Pregnancy Week 39
Baby gains fat ready for birth
Pregnancy Week 40
Baby appears!
The third trimester lasts from week 27 of gestation until your baby finally arrives into the world. Many find this part of pregnancy quite challenging as baby is growing fast and your body adapts for childbirth. During this period, baby will develop all five senses ready for the adventure ahead!