Scan photos are so precious during pregnancy – it's wonderful to see your baby growing and ultrasound pictures can be lovely keepsakes. See how your baby is developing in each week of pregnancy with these ultrasound images, from weeks four to 40.
For parents anxious and excited to see their growing baby, getting a glimpse of your little one on an ultrasound scan is an incredibly special thing. The NHS usually offers two ultrasound scans – one at 12 weeks, and one at 20 – to check your baby's health and, if you want, to predict your baby's sex.
But what does your baby look like the rest of the time? At eight weeks, your growing fetus is still the size of a bean, while at 30 weeks the NHS says that it's grown to the size of a cabbage. Find out what other characteristics your baby is developing each week with these week-by-week pregnancy scans ...
These scans are based on the gestational age, so although it's Week 4 of your pregnancy, you've technically only been pregnant for two weeks.
This is because there's no way of knowing exactly when you conceived, so experts will date your pregnancy from the first day of your last period. Most women conceive around two weeks after this.
So although week 4 is four weeks since the first day of your last period, it's likely only 2 weeks since you conceived.
In the fourth week of pregnancy, the fertilized egg settles in the uterus. Here, just the gestational sac (black) can be seen as the embryo is still too small.
The embryo is now about two millimetres long and usually still not visible on the ultrasound. Nevertheless, the embryo's heart begins to beat this week.
The embryo is now about four millimetres long and the head and neck are already formed.
You can see here the amniotic sac, which is about five millimetres long, with a bean-shaped curved embryo visible.
The embryo now measures about 15 millimetres. It can be seen here from the front – the head is to the left in the picture.
The embryo is about two inches long in the 9th week of pregnancy. The small tail regresses now, and the ears are slowly being revealed. The fetus here is pictured with the head lowered towards the chest.
At 10 weeks, the fetus measures approximately 2.5 centimetres. The head is still huge in size compared to the rest of the body.
In this picture, the head is still inclined towards the chest, but soon it'll gradually begin to raise.
On this ultrasound image, only the legs of the fetus are shown. They are bent at the knees at a right angle, the feet pointing upwards.
The feet are already clearly developed.
Here you can see the head and part of the upper body. You can see the skull bone and the jaw and teeth.
The small nose and mouth are clearly visible at the end of the first trimester, even though the fetus measures only five centimetres.
On this picture you can see the head of the fetus from the top. The two halves of the brain are clear to see.
In this picture you can see a twin pregnancy at 14 weeks, with two gestational sacs clearly visible.
14 weeks pregnant – all you need to know
The image shows the leg of the fetus. The long bones in the upper and lower legs are clearly distinguishable already, as are the toe bones in the foot.
On the ultrasound image, the umbilical cord can be seen. It supplies the baby with nutrients and oxygen and carries away waste products.
On this 3D ultrasound scan, you can already clearly see a little face has formed. The baby now measures about 12cm from crown to rump.
You can see here both hands and one foot. From the bottom right the foot comes into the picture, toes pointing to the left above.
A hand is coming from the top right in the picture, the fingers of both hands fan out to the left.
The fetus is not seen in this picture, but rather the placenta (the entire grey area at the bottom), from which springs the umbilical cord.
In this 3D ultrasound image, the baby seems to be sucking the thumb of his left hand.
You can clearly see two little feet in this scan picture, fully formed at 21 weeks.
The baby's facial profile can be clearly seen in this image.
In this 3D image of a 23-week old fetus, the baby seems to be yawning!
You can quite clearly see the hand and finger bones. By this stage of pregnancy, the baby can now explore his surroundings, suck his thumbs or play with his umbilical cord.
This scan image shows the spine of the baby just over halfway through a pregnancy.
By this stage the baby can now swallow amniotic fluid and often gets the hiccups. On this scan picture you can see how far he opens his mouth.
In the last week of the second trimester (the third trimester begins at 28 weeks) the blood flow in the brain can be clearly seen.
As well as the flow of blood, you can also see other fluids in a scan – in this case you can also see the urine stream of the baby.
Although babies urinate into the amniotic fluid, it is highly sterile.
A little foot can be seen pointing here, no doubt kicking his mum in the ribs!
This 3D ultrasound shows a baby's face and the two little hands.
In this image you can see the baby's face and his eyes are slightly open – by 31 weeks babies open and close their eyes regularly.
In this image you can see the penis of the baby boy.
You can clearly see the profile of the baby in this scan.
Here you can see the baby's little ear, fully formed and getting ready to hear its first sounds outside the womb.
In this picture you can see the child from above the head. The bright points in the image is hair floating in the amniotic fluid.
This scan shows the genital area of a baby girl.
Again, you can see the profile – the baby's face is fully formed now, and if it was born at this point, he would no longer be classed premature.
You can see the baby sucking his thumb in this picture.
In this image you can see the four chambers of the heart and heart valves.
In this image you can see the baby holding his hand to his face.
More on fetal development
Now you've seen what babies look like as they grow and develop in the womb, learn more about fetal development with these articles:
- How big is my baby? Baby size by week
- 12 amazing facts about your unborn baby
- 7 surprising sensations your baby can feel in the womb
- Video: Watch this baby eat, sneeze and cry in the womb
More on pregnancy scans
Wondering when you'll have your first scan, how many scans you'll have throughout your pregnancy, or what to expect when you get there? Learn all you need to know with our guides:
- Ultrasound scans in pregnancy: all you need to know
- How many pregnancy scans will I have?
- Dating scan: your 12-week pregnancy scan
- Anomaly scan: your 20-week pregnancy scan
Scans and your baby's sex
Many parents wonder: when can a scan show if I'm having a boy or a girl? Learn more about scans and sex:
- Skull theory: can it predict if you're having a boy or a girl?
- Nub theory explained: how this sex prediction test works
See more real-life scan pics in our forum – or even share your own! Or check out our articles below:
Incredible post-birth photos show what babies looked like inside the womb
CHAT: Swap scan pics with other parents-to-be here!