At week 5 the embryo measures about 2mm and the cells responsible for the different organ systems are all in one place. The baby develops in a bag called amniotic sac which is a fluid filled cavity that protects the embryo. In week 5, the spinal column and brain are starting to form.
During this time, brain and face develop very quickly, blood vessels are beginning to form and a string of vessel connects your baby to you; this will eventually become the umbilical cord.
At 6 weeks your baby measures 4 mm and has started to look like a curved tadpole. It has a large head and a tail and inside organs have started to form if an ultrasound is done at this point, you may be able to see a beating heart.
The baby’s jaw and eyes have started to develop as well as parts that will later transition into arms and legs. Vertebrae start to form along the baby’s back and a stalk that will later transcribe into the umbilical cord is also developing at this point.
At 7 weeks, your baby is about 1 cm tall and with the brain developing rapidly the head is much bigger than the baby’s body. The baby has large eyes, a big forehead, and parts that will later develop into ears. The baby has nostrils and eyes at this point and also has lips while the brain, spinal cord and internal organs are transcribing including the stomach, kidneys, and lungs.
What is an amniotic sac? The baby is lying in an amniotic sac which is a fluid filled membrane-lined bag. What is a placenta? A placenta has started to form and is attaching to the uterus from the inside so it can deliver food and oxygen to the baby. You will be happy to know that your baby’s heart is beating at 150-180 beats/minute.
At 8 weeks of pregnancy, the baby is 1.3 cm tall and still looks like a tadpole while the tail is slowly getting smaller to disappear soon. The eyes, nose, inner ear and tongue are developing while the mouth is coming together with the upper jaw. There are hands at the end of the parts that will now develop into arms.
The arms and legs are developing cartilage at this point. Reproductive parts are also developing but we cannot tell whether the baby is a boy or a girl yet. The fetus lies inside the amniotic sac and is getting its food from the yolk sac. All this time, the placenta is constantly developing and will attach to the uterus.