Develops from both the mother and the baby,
Embeds itself into the uterine wall

Attaches to the baby via the umbilical cord, however there is no mixing of maternal and foetal blood. This is because the maternal blood is at a much higher pressure. If the baby was connected to his mother’s circulatory system, his blood vessels would burst.

The foetus and the mother can, however, have different blood groups, but you would know about this if this was the case. (Rhesus Negative/Positive).

The mother’s blood flows into the spaces in the placenta and the baby’s blood is carried by the umbilical artery into villi, capillaries that project, ‘finger-like’, into the placental space.
Creates a large surface area of a thin barrier between the two circulations, enabling essentials for healthy growth, such as oxygen and nutrition to enter the baby’s blood system by diffusion.

In turn, the baby needs to dispose of waste – the carbon dioxide being constantly produced in all their cells, as well as the amniotic fluid which is drunk and then excreted. This waste passes through the thin walls of the villi into the mother’s circulatory system and she gets rid of it.

Through this method of exchange, the baby is also given the mother’s antibodies, providing immunity to a host of bacteria it hasn’t even come into contact with yet. However, drugs can also cross the placenta, which is why it is so important mothers avoid these during pregnancy.

During the 3rd stage of labour the placenta is birthed.
Amazing organ.
You may have the chance to look at it or you may be encapsulating it.
Around the size of a dinner plate, approx. 3cm thick and reddish blue in colour with two types of membranes attached to it – the amnion (filled with fluid) which surrounds the baby and the chorion which in turn surrounds the amnion.
The baby’s side of the placenta is relatively smooth whilst the side that has been attached to the uterus has lumps and bumps of arteries and veins running across it.