O43.0: Placental transfusion syndromes

The placenta forms in the mother’s womb during pregnancy. The placenta consists of cells from the mother and cells from the unborn child. The umbilical cord connects the child to the placenta. During pregnancy the umbilical cord connects the child's blood circulation to the mother's. The child receives nutrients and oxygen via the blood vessels in the umbilical cord.

An exchange of blood can occur when the pregnancy involves twins, for example. In this case, the blood circulation systems of the twins are connected to each other by the placenta. As a result, blood flows from one twin to the other. If the twins have separate amniotic sacs, there can be differing amounts of amniotic fluid in the sacs as a result. When the pregnancy begins, the amniotic sac containing the amniotic fluid develops in the womb. The amniotic sac surrounds the child. If blood flows from one twin to the other, the twins may be different sizes. One of the twins may receive less oxygen. Defects can also occur in one or both twins.

A blood exchange can also occur between mother and child. The mother's blood and the child's blood do not usually come into direct contact. Nutrients and oxygen are exchanged via the placenta. When blood is exchanged between the mother and child, the child's blood can get into the mother's circulatory system. This can happen during pregnancy or during the birth. If the child's blood gets into the mother's circulatory system, the child may then receive less oxygen. When blood is exchanged during pregnancy, the child may move about less than before in the womb.

The mother's blood can also get into the child's circulatory system. This can also happen during pregnancy or during the birth. The child may have too much blood in its body.