By week 5, your baby has burrowed into the wall of your uterus. It is now called an embryo and measures about 2mm from end to end. The foundations for all of the major organs are in place. The baby is inside an amniotic sac, a bag of fluid that protects it.
The cells in the baby are still dividing. In week 5, the brain and spinal column are already starting to form. The spinal cord is called the neural tube and is developing as an open groove. Your baby’s head is much larger than the rest of the body at this stage as the brain and face are developing very rapidly.
Your baby’s heart will start beating this week. The blood vessels are already starting to form and blood is circulating in the baby’s body. A string of blood vessels connects you to your baby, and this will eventually become the umbilical cord.
Your baby at 5 weeks
Week 5 is when most women start to wonder whether they may be pregnant. You will have missed your period, but you may be feeling like it’s just about to start. You may notice your breasts are larger and feel sore, and you may be feeling quite tired.
You will also be producing more human chorionic gonadotropin (hCG).
Things to remember
You can do a pregnancy test the day after you miss your period. There are many different tests available, so make sure you follow the instructions carefully.
If the pregnancy test shows you’re pregnant, it’s a good idea to see your doctor as soon as possible. They will confirm you are pregnant and advise you on how to look after yourself and your baby.
Finding out you’re pregnant can be very exciting. But for some women, pregnancy is unplanned. Whether the baby was planned or not, you may feel a range of emotions from joy to surprise to shock.
Your pregnancy at 6 weeks
Learn about your pregnancy journey and what is happening to you and your baby.
Speak to a maternal child health nurse
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Last reviewed: August 2020