What is the placenta?

The placenta is a temporary body organ that develops during pregnancy. It attaches to the lining of your uterus and delivers oxygen and nutrients to your growing baby through the umbilical cord.

The placenta is flat, round, brown and looks a bit like a cushion. At the end of your pregnancy an average placenta will measure around 20cm in length and weigh about 500g.

If something goes wrong with the placenta, it can be serious and even life-threatening for both you and your baby.

When does the placenta form?

The placenta develops alongside your baby in your uterus from the very beginning of your pregnancy. It starts forming at the time your fertilised egg implants in your uterus. While your placenta develops, a group of cells called the corpus luteum serves as the main source of hormones and nourishment for your baby. By about 10-12 weeks, the placenta is well developed and takes over supporting your baby.

It is also known as the 'afterbirth'. Once your baby is born, the placenta is no longer needed. It is pushed out naturally or with help from your midwife after the birth of your baby.

What is the role of the placenta during pregnancy?

The placenta has many roles including:

• passing oxygen, nutrients and antibodies from your blood to your baby
• carrying waste products such as carbon dioxide from your baby back to your blood, so your body can get rid of them
• to help prevent some harmful substances, such as viruses and toxins (poisons), from reaching your baby
• making the hormones that are needed for pregnancy, birth and preparing for breastfeeding

How does the placenta work in twin and other multiple pregnancies?

An ultrasound can help identify what type of multiple pregnancy you are having and if you have one or more placentas.

Fraternal twins or other multiple pregnancies come from separate eggs, and each have their own placenta. Identical twins or multiple pregnancies come from the same egg that splits after fertilisation, so they may share a placenta, or each have their own.

Can medicines and other substances cross the placenta?

Alcohol, nicotine, and some medicines and other drugs can cross the placenta and affect your baby's health.

Because alcohol can affect your placenta, you should not drink alcohol when you're pregnant. Read more on alcohol and pregnancy.

Smoking or vaping during pregnancy can harm both you and your baby. Cigarette smoke and vapour from e-cigarettes, also known as vapes, contain poisonous chemicals, including nicotine. The chemicals can cause pregnancy complications and may affect your baby's development. The best way to protect your baby and yourself is to avoid or quit smoking and vaping.

Let your doctor and pharmacist know that you are pregnant, so that they only prescribe and dispense medicines that are safe for your baby. Read more on medicines during pregnancy.

Can anything go wrong with my placenta?

Abnormalities with the placenta vary and most of these are out of your control. They include:

• where it attaches in the uterus
• its structure (for example, in cases of twins)
• how it functions and its effects on you and your baby

What can go wrong with the placenta?

Problems with your placenta can happen during pregnancy, birth or after birth. These are potentially dangerous for both you and your baby:

• Placental abruption is when some or all the placenta comes away from the wall of the uterus before your baby is born.
• Placenta praevia is when the placenta partially or totally covers the cervix (the opening of the uterus).
• Placental insufficiency is when the placenta doesn't work properly during pregnancy, and your baby may not get enough oxygen and nutrients needed to grow and develop.
• Placenta accreta is when the placenta attaches too deeply into the wall of the uterus. This can lead to severe bleeding during or after birth and can be life-threatening.
• Retained placenta is when part or all of your placenta does not come out after the birth. This might be because it is stopped by your cervix or is still attached to your uterus.

Vaginal bleeding during late pregnancy is often due to a problem with your placenta. If you experience bleeding, contact your doctor or midwife as soon as possible for advice and support.

What can I do to keep my placenta healthy during pregnancy?

Here are some tips to help keep your placenta healthy during pregnancy:

• Keep all your health appointments, and visit your healthcare provider regularly during pregnancy. That way, if there are complications, they can be identified during these appointments.
• Tell your doctor if you have had problems with the placenta in a previous pregnancy, or if you have had any surgery to your uterus, such as a caesarean.
• Avoid smoking, drinking alcohol or taking drugs during pregnancy, since they can increase your chance of complications with the placenta or your baby.
• Always consult your doctor or pharmacist before you take any medicine during pregnancy, including over-the-counter medicines, natural therapies and supplements.

What happens to the placenta after my baby is born?

After your baby is born, you will need to birth your placenta. This is called the third stage of labour. This stage of labour can be managed in different ways.

Your health team will explain your options to you — this is known as 'informed consent'. Informed consent means that you will be given enough information about your choices to make decisions about your health and healthcare. Then, using a process called shared decision making (SDM), you will make healthcare decisions together with your health team. SDM means that you are involved in important health decisions that concern you. SDM considers your values, goals and culture, as well as the evidence about the treatment available to you.

If you had a vaginal birth, your placenta will usually come out after some mild contractions and a few pushes (also called physiological third stage). You may also be offered an injection of synthetic oxytocin to help the placenta come out more quickly. This is called active management. Active management reduces your chance of having a postpartum haemorrhage (severe bleed). It is your choice how you birth your placenta, although in some cases you doctor or midwife may recommend active management, particularly if you have had pregnancy complications.

If you have a caesarean section, your doctor will remove the placenta at the same time your baby is born.

Once you birth your placenta, your doctor or midwife will check that it looks complete. If they are concerned that your placenta isn't complete, they may suggest further investigations.

If part of the placenta doesn't come out, you may need to have it surgically removed to prevent infection.

Can I take my placenta home with me?

It is your choice what you do with your placenta. You may choose to take your placenta home with you. In most cases, it is safe to do this if you follow basic health and safety rules. You can speak to your doctor or midwife to arrange this. You can speak to your doctor or midwife to arrange this.

In some cultures, people bury the placenta in a special place.

Some people take their placenta home to eat or have it encapsulated (put into capsules to eat) by an external company. There is no proven health benefits, but you may choose to do this for cultural, spiritual or personal reasons. If you want to keep your placenta for eating, tell your midwife before you give birth. Your midwife needs to use clean gloves and put the placenta in your cooler right away. Treat the placenta like fresh, raw meat and place it in your cooler as soon as possible, but don't store it in a fridge with other food.

Resources and support

For more information or support:

• The Royal Women's Hospital has further information on placenta problems and taking your placenta home.
• Westmead Hospital in NSW has further information about medical problems in pregnancy including problems with the placenta.

Do you prefer to read in languages other than English?

• The NSW Government offer a Having a baby book in English and other languages.