Growth is rapid during the sixth week, during which your baby will triple in size. Formation of baby' s facial features is in its early stages. Optic vesicles, which later form the eyes, are beginning to develop. Passageways that will make up the inner ear also are beginning to form. When 6 weeks pregnant, an opening for the mouth is formed by the in growth of tissue from above and from the sides of the face. Below the mouth, where the neck will develop, are small folds that ultimately will become your baby’s neck and lower jaw.
By the sixth week of your pregnancy the neural tube along your baby’s back has closed over. The brain is growing rapidly to fill the now-formed, enlarging head. Your baby’s brain is also developing distinct regions. In the front of the chest, your baby’s heart is pumping rudimentary blood through the main blood vessels and beating at a regular rhythm. The beginnings of the digestive and respiratory systems are forming. In addition, 40 small blocks of tissue are developing along your baby’s mid line. These will form the connective tissue, ribs and muscles of your baby’s back and sides. Small buds that will grow into your baby’s arms and legs are now visible. By the sixth week of your pregnancy, four weeks after conception, your baby is about 1/8 of an inch long.
If you are suffering from morning sickness, you may find that the smell of certain things, such as tobacco smoke or frying food, brings on the sickness or makes it worse. Your skin may become dry and flaky, or you may get spots. Now is the time to start thinking about your antenatal care, and the type of birth you want.
The heart has now formed in the chest cavity and is beginning to beat. By the end of week 6 the stalk connecting the embryo to the placenta will have begun to grow into the umbilical cord and blood vessels will have started to form. The embryo is now about the size of your little fingernail and its movements can be picked up by ultrasound scan. The head has the beginning of the eyes, ears, and mouth and there are tiny buds which will become arms and legs.