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Placenta complications in pregnancy

3-minute read

The placenta is an extraordinary organ that develops inside your uterus (womb) when you are pregnant. It provides your baby with nutrients and oxygen from your blood. When something goes wrong with the placenta, it can be serious and even life-threatening both to the mother and the baby.

What's normal?

The placenta is normally attached to the top or side of the uterus and connects to the baby through the umbilical cord. By the time the baby is born, a normal placenta will weigh between 700 and 800 grams.

In a normal birth, the placenta is delivered through the vagina, usually 5 to 30 minutes after the baby is born. This is known as the third stage of labour. If you have a caesarean, the doctor will remove the placenta at the same time as the baby.

What's not normal?

Sometimes the placenta does not grow as it should. This can affect the growth and health of the baby, and cause complications during birth.


  • Placenta accreta: When the placenta grows too deeply into the wall of the uterus. This can lead to massive blood loss during or after delivery and can be life-threatening.
  • Placental abruption: When the placenta peels away from the wall of the womb before delivery. This can cause bleeding and will mean your baby may not be getting all the nutrients they need. In some cases, an early delivery may be needed.
  • Placenta praevia: When the placenta partially or totally covers the cervix, the opening through which the baby will come out. This condition is more common early in pregnancy and often resolves as the placenta moves higher in the uterus as the uterus grows. If the placenta is still covering the cervix close to the time of delivery, a caesarean section will be necessary.
  • Placental insufficiency: When the placenta doesn’t work properly during pregnancy, depriving the baby of oxygen and nutrients. This can affect the growth of the baby.
  • Retained placenta: The placenta may not come out after the birth because it is blocked by the cervix or it is still attached to the uterus. This can cause severe infection or blood loss, and can be life-threatening.

How will I know there is something wrong with my placenta?

There are signs you should look out for during your pregnancy that might indicate there is a problem with your placenta. In some cases, you might not know anything is wrong and it is something your doctor finds during routine antenatal tests and ultrasounds.

The main signs that something may be wrong with the placenta are:

  • bleeding from your vagina, which may range from quite light to very heavy, depending on the problem
  • pain, either in your tummy or back
  • contractions

Some women have bleeding but no pain; others may experience sudden and very severe abdominal pain but no bleeding. If you have any of these symptoms, seek medical attention immediately.

What to do if you think there may be a problem

If you have any vaginal bleeding during the second or third trimester, it’s important to see your doctor as soon as possible. If the bleeding is severe and you have significant pain, call triple zero (000) for an ambulance or go to your nearest hospital emergency department.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: February 2020

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Need more information?

Retained placenta

A retained placenta is when part or all of the placenta is not delivered after the baby is born. It can lead to serious infection or blood loss.

Read more on Pregnancy, Birth & Baby website

Placenta previa - Better Health Channel

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Placenta praevia

Placenta praevia is a condition where the placenta lies low and may cover the cervix, blocking the baby's exit during birth.

Read more on Pregnancy, Birth & Baby website

What is the placenta?

The placenta is crucial to keeping your baby alive and well during pregnancy. Read more here.

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Placenta accreta

Placenta accreta is a serious but rare pregnancy complication that causes heavy bleeding. If you have it, you will need special care at the birth.

Read more on Pregnancy, Birth & Baby website

Placental insufficiency

Placental insufficiency occurs when the placenta does not work properly and your baby doesn't get the oxygen and nutrients they need.

Read more on Pregnancy, Birth & Baby website

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If a woman drinks during pregnancy the alcohol crosses the placenta to the baby. But what about the effect of alcohol on men?

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Placental abruption

Placental abruption is when some or all of the placenta peels away from the uterus wall before birth. It can deprive the baby of oxygen and nutrients.

Read more on Pregnancy, Birth & Baby website

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Starting approximately two weeks after conception, a hormone called human chorionic gonadatropin (hCG) hormone is produced by the developing placenta and can be detected in urine and in blood

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4 weeks pregnant: Key points

When you are 4 weeks pregnant your body and your new baby are undergoing rapid changes. The placenta forms and begins producing a hormone called human chorionic gonadotrophin (hCG), which is the substance a pregnancy test detects to confirm you are pregnant. The cells which are growing into your new baby establish membranes which connect them to the placenta and prepare themselves for differentiation into different types of cells, which will occur next week when you are 5 weeks pregnant. These developments may cause you to experience unusual emotions and also cause changes in your body such as darkening of the areolas of your nipples.

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The information is not a substitute for independent professional advice and should not be used as an alternative to professional health care. If you have a particular medical problem, please consult a healthcare professional.

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