Week 4 of Pregnancy

What is happening with the baby’s development in the 4th week? 

The baby which is called an embryo at this point is about the size of a poppy seed or measuring only about 0.04 to 0.1 inches (1 to 2.5 millimeters) in length. It has just finished implanting into the wall of your uterus. This is a critical step and after this stage the pregnancy has been established. 

At 4 weeks of pregnancy there is a lot going on inside this tiny embryo.  Cells are rapidly dividing and as they are formed they are beginning the creation of important structures. 

The beginning of the amniotic sac has begun which will eventually surround and protect the growing fetus. The newly divided cells will also start the beginning of what will become the placenta. 

The start of the formation of the neural tube happens at this time as well. This structure will turn into the brain, spinal column and nervous system.