You might notice some changes in your own body, too. Some of those early pregnancy symptoms could start to fade, and you may even have a bit more energy. Even if you can’t actually see what’s happening inside yet, it’s still pretty amazing to know your baby has reached this stage. It’s worth taking a moment to just appreciate the progress.
Transition from Embryo to Foetus
Around the ninth week of pregnancy, your baby reaches an important stage. This is when the embryo becomes a foetus. Up until now, your baby has been forming the main organs and body structures. From this point, the focus shifts to growth and development, as those early features start becoming more defined.It begins when a sperm fertilises an egg in your fallopian tube, creating a zygote. This single cell divides rapidly and becomes a blastocyst, which attaches to your uterus. By the end of the eighth week, it is called an embryo with the early stages of organs and systems in place. At week nine, it is known as a foetus, ready to continue growing and developing each day!
The Embryonic Stage
Before your baby becomes a foetus, it goes through the embryonic stage, which lasts from conception to the end of the eighth week. This is a busy time when the basic foundation of your baby’s body starts forming.This is what happens during these early weeks:
Weeks 1 to 4
In the first two weeks, your body prepares for pregnancy as hormones get your uterus ready. Around week three, fertilisation takes place, and the zygote begins to divide while travelling toward your uterus.By week four, the blastocyst implants itself, and the amniotic sac and early placenta start forming to protect and nourish your baby.
Weeks 5 to 8
This is when your baby starts to look more human. By week five, the neural tube forms, which will later develop into the brain and spinal cord.Around week six, tiny buds appear that will grow into arms and legs, and the heart starts beating at about 110 beats per minute.
By week seven, bones begin to form, replacing the soft cartilage. The embryo still has a small tail and a large head at this stage.
By the end of week eight, all the major organs and systems are in place, and the umbilical cord is fully developed to carry oxygen and nutrients to your baby.
The Foetal Stage
Once your baby becomes a foetus around week nine, development moves into the next phase. The basic structures are already formed, and now the focus is on growth and refinement. This stage continues from week nine until birth, and it’s when your baby starts to look more like the little person you’ll soon meet.Weeks 9 to 12
During this time, your baby grows rapidly. Facial features, limbs, muscles, and bones begin to take shape. Around week nine, little teeth and taste buds begin to form. The head now starts to look more balanced.By week ten, your baby already has tiny fingers and toes with small nails growing in. Around week eleven, your baby can open and close their mouth and even make a tiny fist.
The major organs are working by week twelve, like the liver starts making bile, and your baby begins to swallow and pass small amounts of amniotic fluid.
Why This Transition Is a Big Deal
The change from an embryo to a foetus is a big milestone. It means your baby has passed the most delicate stage of development. During the embryo phase, your baby is very sensitive to harmful substances that could cause birth defects.Once the foetal stage starts, all the major organs are formed, and the focus shifts to growth and development. Your baby is now a bit stronger, though still affected by your health and surroundings.
Here’s why this stage is so special:
- Lower miscarriage risk: After the first trimester (around 12 weeks), the risk of miscarriage drops significantly because your baby’s major organs have already developed.
- Human features emerge: Your baby now starts to look more human, with a defined face, arms, and legs.
- Systems start working: The circulatory, digestive, and urinary systems begin to function, and your baby starts practising simple actions like swallowing amniotic fluid.
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FAQs on Goodbye Embryo, Hello Foetus: A Big Milestone
- What scans or tests are done during foetal stage?
During the foetal stage, common tests include ultrasounds such as the dating scan, Nuchal Translucency (NT) scan, and the 18 to 22 week anomaly scan. - How does maternal health impact foetal growth?
Foetal growth is influenced by maternal health, including diet, stress levels, infections, and existing medical conditions.