We've all heard of the placenta, but what exactly is it, and what does it do? Read on and be impressed by the many crucial jobs this temporary yet vital organ accomplishes.

What is the placenta?

The placenta is an organ that develops and exists solely during pregnancy. Also called the ‘afterbirth’, it’s an incredibly complex and important organ that plays a crucial role throughout the pregnancy in nurturing and protecting the developing baby.

The placenta is attached to the wall of the uterus and delivers oxygen and nutrients through the umbilical cord, which connects the baby to the placenta. As the baby grows, so does the placenta, and it ends up being about 22cm long and 2.5cm thick and weighing about half a kilogram. 

What does it do?

The placenta has been described as the ‘interface’ between mother and baby. The mother’s blood is pumped through the placenta, which filters oxygen, glucose and other nutrients and directs them to the baby through the umbilical cord.

This amazing organ keeps the mother’s blood separate from the baby’s blood so that the baby is protected against infections and toxins. It also removes waste products such as carbon dioxide from the baby's blood and produces necessary pregnancy hormones including oestrogen, progesterone and lactogen. Then, as the pregnancy nears its end, the placenta does one of its final, vital jobs – providing antibodies to the baby to protect it after birth.

What happens to the placenta after the birth?

Usually about five to 30 minutes after the birth of the baby, the placenta is expelled from the mother’s body in stage three of labour. If you deliver your baby vaginally, the placenta will also be delivered vaginally, with the uterus undergoing some further mild contractions to push the placenta out. If you have a caesarean, the placenta will be removed during the procedure.

Can things go wrong?

There can be some complications involving the placenta that are potentially dangerous to both mother and baby. Some of them are as follows:

Placenta accreta: Sometimes the placenta is not attached properly to the uterus, and this can cause serious and sometimes even fatal blood loss during or after delivery.

Placental abruption: During pregnancy, the placenta can sometimes separate from the uterus wall. This causes bleeding and means the baby might not be getting all the necessary nutrients and may need to be delivered early.

Placenta praevia: The placenta can sometimes partially or totally cover the opening to the uterus (the cervix) and can prevent the baby from being born vaginally. In these cases, a caesarean section is carried out.

It’s important to follow a healthy lifestyle during pregnancy to help the placenta stay healthy too and to be aware of and seek medical advice for any symptoms such as vaginal bleeding, uterine contractions or abdominal or back pain.

Did you know?

  • Only mammals grow a placenta during gestation, and most animals eat the placenta after their offspring are born. This is known as ‘placentophagy’.
  • Some people eat placentas too. There is a rare practice, known as ‘human placentophagy’, in which the placenta is cooked and then eaten, and some commercial service providers will take your placenta and return it as capsules for you to swallow. Ingesting a placenta is believed by some people to provide health benefits, but the practice is not supported by the medical or healthcare profession. The Australian Therapeutic Goods Administration warns of potential health and legal risks resulting from the practice.
  • Scientific research has not found evidence of any health benefits, but there is a known risk of infection, so it’s best to leave the practice of placentophagy to the animal kingdom.