Fetal-maternal haemorrhage

Foetal-maternal haemorrhage is the loss of foetal blood cells into the maternal circulation. It takes place in normal pregnancies as well as when there are obstetric or trauma related complications to pregnancy.

Normally the maternal circulation and the foetal circulation are kept from direct contact with each other, with gas and nutrient exchange taking place across a membrane in the placenta made of two layers, the syncytiotrophoblast and the cytotrophoblast. Foetal-maternal haemorrhage occurs when this membrane ceases to function as a barrier and foetal cells may come in contact with and enter the maternal vessels in the decidua/endometrium.