During this period, it takes approximately 11 to 15 days for the zygote to attach to the uterine wall, allowing the zygote to form an attachment. The next stage of prenatal development is the embryonic period. This is the period of prenatal development that occurs two to eight weeks after conception. During this period, cells multiply at a rapid rate, support systems begin to form, and organs begin to appear. It is during this period that the umbilical cord, the survival system that connects the baby to the placenta, is formed. The placenta allows small blood vessels to pass from mother to baby. This is how the baby can get food from its mother. Mothers should be very careful about what they eat and drink, because everything they do will affect their baby. If they drink or take drugs, it can seriously affect the baby's development. By the time most women find out they are pregnant (5-8 weeks), their organs have already started to form. “At about 21 days, the eyes start to appear and after 24 days, the heart cells start to differentiate. » During the fourth week, the arms and legs will grow. At eight weeks, the body is just 2.5cm long and the face has started to develop..