The placenta is a temporary organ that forms in your uterus during pregnancy. It attaches to your uterine wall and provides nutrients and oxygen to your baby through the umbilical cord. Certain conditions of the placenta can cause pregnancy complications.


Location of the placenta in the uterus during pregnancy.
The placenta is an organ that develops in the uterus during pregnancy. It provides food and oxygen to the fetus.

What is the placenta?

The placenta is a temporary organ that connects your baby to your uterus during pregnancy. The placenta develops shortly after conception and attaches to the wall of your uterus. Your baby is connected to the placenta by the umbilical cord. Together, the placenta and umbilical cord act as your baby's lifeline while in the uterus. Functions of the placenta include:

  • Provides your baby with oxygen and nutrients.
  • Removes harmful waste and carbon dioxide from your baby.
  • Produces hormones that help your baby grow.
  • Passes immunity from you to your baby.
  • Helps protect your baby.


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When does the placenta form?

The placenta begins to form after a fertilized egg implants in your uterus around seven to 10 days after conception. It continues to grow throughout your pregnancy to support your baby. The placenta starts as a few cells and grows to be several inches long.

When does the placenta take over?

The placenta takes over hormone production by the end of the first trimester (12 weeks of pregnancy). Up until this time, the corpus luteum handles most of the hormone production. Many people's first-trimester symptoms of nausea and fatigue go away once the placenta takes over in the second trimester.


What does the placenta do?

The placenta helps to keep your baby alive and healthy during pregnancy. Your blood passes through the placenta and provides oxygen, glucose and nutrients to your baby through the umbilical cord. The placenta can also filter out harmful waste and carbon dioxide from your baby's blood. The placenta enables the exchange of oxygen and nutrients between the bloodstreams of you and your baby without ever mixing them. It acts as your baby's lungs, kidneys and liver until birth.

As you get closer to delivery, the placenta passes antibodies to your baby to jumpstart its immunity. This immunity sticks with your baby for the first several months of life.

The placenta produces several important hormones like lactogen, estrogen and progesterone during pregnancy. These pregnancy hormones are beneficial to both you and your baby. For example, the placenta produces a hormone that suppresses milk production during pregnancy.


Does the placenta move?

Sort of. The placenta appears to move only because the uterus expands as the pregnancy and fetus grow. Your healthcare provider will look at the location of your placenta during your 20-week anatomy ultrasound and determine if its position may cause complications. Most placentas move to the top or side of the uterus by 32 weeks of pregnancy.


Where does the placenta form?

The placenta can form anywhere in your uterus. It develops wherever the fertilized egg implants into your uterine wall. Some of the positions of the placenta are:

  • Posterior placenta: The placenta grows on the back wall of your uterus.
  • Anterior placenta: The placenta grows on the front wall of your uterus closest to your abdomen.
  • Fundal placenta: The placenta grows at the top of your uterus.
  • Lateral placenta: The placenta grows on the right or left wall of your uterus.

The placenta can move up until about 32 weeks of pregnancy. It's common to have a placenta that moves upwards and away from your cervix as your baby gets bigger.


What does the placenta look like?

The placenta looks like a disc of bumpy tissue rich in blood vessels, making it appear dark red at term. Most of the mature placental tissue is made up of blood vessels. They connect with the baby through the umbilical cord and branch throughout the placenta disc like the limbs of a tree.

What color is the placenta?

The placenta has two sides: the side attached to your uterus and the side closest to your baby. The side attached to your uterine wall is a deep reddish blue color, while the side facing your baby is gray.

How big is a normal placenta?

The placenta is about 10 inches long and 1 inch thick at its center. It weighs around 16 ounces (1 pound) by the time your baby is born.

What is the placenta made of?

The placenta begins to develop when the fertilized egg implants into your uterine wall. The placenta contains mostly blood vessels contained within structures called “villi.” The blood vessels connect with the baby’s bloodstream through the umbilical cord. The rest of the placental tissues mainly connect the villi to the umbilical cord and allow your blood to bathe the villi, supplying the baby with oxygen and nutrients.

Conditions and Disorders

What are common conditions and disorders of the placenta?

An issue with your placenta can be dangerous for both you and your baby. Some of the complications associated with the placenta are:

  • Placenta previa: The placenta covers all or part of the cervix. It's sometimes called a low-lying placenta.
  • Placenta accreta: The placenta attaches too deeply to the wall of your uterus.
  • Placental abruption: A condition during pregnancy when the placenta separates from the uterus too early.
  • Placental insufficiency: When the placenta isn't providing enough nutrients or oxygen to your baby.
  • Retained placenta: When part of the placenta stays inside your uterus after pregnancy.

Tell your healthcare provider if you've had surgery on your uterus or vagina or if you've had problems with your placenta in prior pregnancies.

What are the most common signs of a placenta disorder?

Bleeding from your vagina is the most common sign that there is a problem with the placenta. Not everyone experiences bleeding, so it's important to discuss your pregnancy symptoms with your healthcare provider. Symptoms like abdominal pain or contractions could also mean there is a problem with the placenta. In some cases, a baby that measures too small for dates suggests a problem with the placenta.

How are conditions of the placenta treated during pregnancy?

Treating a condition of the placenta varies during pregnancy. In most cases, it's dependent on the severity of the condition and how far along you are in pregnancy. Your healthcare provider will monitor you and your baby closely to make sure you are both safe. Some of the treatments for placental issues during pregnancy could include:


What types of substances are bad for the placenta?

Medicine, drugs, alcohol and nicotine can all transfer from your bloodstream to your baby through the placenta. Talk to your healthcare provider before taking any prescription or over-the-counter medications (including vitamins and supplements) during pregnancy. Drinking alcohol or smoking cigarettes is not recommended during pregnancy.

How is the placenta delivered?

The placenta is delivered shortly after your baby is born (usually between five and 30 minutes after). This is called the afterbirth or the third stage of labor. If you've delivered your baby vaginally, your uterus will continue to contract to expel the placenta. Your healthcare provider may push on your belly or ask you for one final push. If your baby was born via C-section, your healthcare provider removes the placenta through the incision used to deliver your baby. In rare cases, parts of the placenta stay in your uterus after delivery. This can cause bleeding, pain and infection.

Additional Common Questions

Why do people eat their placenta?

Some people believe that eating or swallowing the nutrient-rich placenta offers health benefits. The placenta can be cooked or encapsulated into pills and swallowed like a vitamin. There aren't any studies that confirm eating your placenta delivers health benefits. It may be harmful to you. Talk to your healthcare provider before making any decisions about eating or encapsulating your placenta.

What happens to the placenta after birth?

In most cases, your placenta is thrown away after birth. However, some people choose to bank placental tissue through a stem cell bank. Placental tissue banking is when tissue and blood from the placenta are collected and stored after delivery. The placental tissues are rich in stem cells that can treat certain diseases and life-threatening conditions. Sometimes your doctor might ask a pathologist to examine the placenta if you or your baby have conditions like fever or illness, if the baby is born premature, or if the baby is small for gestational age.

A note from Cleveland Clinic

Your placenta is the lifeline between you and your baby. It's a vital organ that provides your baby with nutrients and oxygen until birth. Certain conditions during pregnancy can affect your placenta and cause it not to work as well as it should. Talk to your healthcare provider if you have any questions about the placenta, its function, or any placental complications. They can check to make sure your placenta is functioning as it should and explain how it works during pregnancy.

Medically Reviewed

Last reviewed on 02/04/2022.

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