By the end of the 8th week of pregnancy, a baby is considered a fetus. During the 9th and 12th week of pregnancy - the latter part of the first trimester - structures that have already formed continue to grow and develop.
A baby’s development during the 9th to 12th week of pregnancy are described in more detail below.
Week 9
During the 9th week of pregnancy, the face is slowly forming with the eyelids and ears continuing to develop.
The eyes are larger, more distinct and may have some pigment. The mouth and tongue can also be seen and very small taste buds are present.
The arms grow and a bend can be seen at the elbows. The feet and hands are developing, with ridges present where the fingers and toes will grow.
The main internal organs such the lungs, heart, kidneys, brain and gut all continue to develop. At this stage, the baby may have grown to around 200mm in length.
Medical accurate 3d illustration of a fetus week 9. Image Copyright: Sebastian Kaulitzki / Shutterstock
Week 10
By week 10, the baby’s head has become more round and a neck starts to form. The eyelids can now close to protect the developing eyes and the ears start to develop.
The upper lip and nostrils are visible and the milk teeth are already present in the jawbone.
The heart is completely formed and beating at around 180 beats per minute (bpm) and the baby’s movements can be observed on an ultrasound scan.
Week 11
At the start of week 11, the baby’s head is still very large, accounting for around one half of its length, although the body is about to grow quickly, catching up over the next few weeks.
The baby’s eyes are now clearly separated, the facial bones are formed and the ears are low set.
The liver is now starting to form red blood cells and by the end of week 11, the baby’s genitalia will have started to develop. The baby now weighs around 8 grams.
Week 12
At 12 weeks, the baby is forming fingernails and the face now appears human. The fetus is fully formed with all of its organs being well developed.
The baby may be around 60mm in length and weigh around 14 grams. The baby is moving, although the mother cannot yet feel this. The cartilage the baby has developed now starts to turn into bone.
Belly of a pregnant woman on 12 week (3 month). Image Copyright: Noiz Stocker / Shutterstock
The mother’s body
Between 9 and 12 weeks of pregnancy, the mother’s breasts will have enlarged and maybe become tender.
She may also have experienced changing emotions, feeling content one moment but unhappy the next, although these emotions should start to settle down.
Pregnant women should have attended their first antenatal care appointment by 12 weeks and should contact their doctor or a maternity team member if they have not done so yet.
The first ultrasound scan is offered somewhere between 8 and 14 weeks of pregnancy. During the first antenatal appointment, the woman is offered various checks and tests to monitor health and identify any potential difficulties.
The antenatal team will also discuss with the mother all the options regarding where she would like to have the baby.
Further Reading
Antiseizure medications in pregnancy tied to child neurodevelopment risks