What Is Placenta and What are The Types of Placenta

What Is Placenta and What are The Types of Placenta

10 Aug 2018 | 9 min Read

Sayani Basu

Author | 607 Articles

During pregnancy, you are nurturing and supporting your baby within you. However, there’s something else growing in your uterus too that is responsible for keeping your baby alive.

Yes, we are talking about placenta. It is an organ attached to the lining of the womb. It delivers oxygen and nutrients to your developing baby. Read on to know more about placenta and its types.

What is Placenta?

The placenta is a pancake-shaped organ that is made up of blood vessels. It provides the unborn baby nutrients, water, oxygen, antibodies against diseases and a waste removal system. 

The placenta develops in the uterus during pregnancy. You may have two placentas if you are pregnant with twins.

If you are carrying identical twins, the number of placentas depends on the time when the fertilised egg splits. If the placenta has already formed when the embryo splits in two, one placenta will sustain both twins. If the split happens earlier, you might have two placentas, one for each baby.

Different Types of Placenta Position

A pegnancy ultrasound (at the 12 week and the 20 week scans) can determine the position and structure of placenta. Most commonly the placenta is located at the top of the uterus (fundus). The other types of placenta position are:

  1. Anterior: Anterior placenta occurs when the placenta implants into the front of your uterus. Although an anterior placenta does not have a negative impact on birth, it may:
  • Make it difficult for you to feel your baby as the baby is cushioned by your placenta at the front of your stomach.
  • Make your baby’s spine against your spine. This can increase the chances of having a longer and painful labour or a caesarean section.

  1. Posterior: A posterior placenta occurs when the placenta implants onto the back of your uterus. The blood flow at the back of the uterus can at times be less efficient due to the wall being longer and thicker. This might increase the chance of a preterm labour.

  1. Lateral: A lateral placenta occurs when the placenta implants on the left or right side of the uterus. Being a rare possibility, studies have found that lateral placental position places women at an increased risk of having a breech baby.

  1. Previa: Placenta previa occurs when the placenta implants over the cervix. Some of its causes are carrying twins or triplets, maternal age being greater than 35 years, history of placenta previa, previous caesarean delivery and smoking during pregnancy.
The placenta plays an important role in supporting the unborn baby throughout pregnancy. | Image Source: freepik

Importance of Placenta and How It Works

Connecting your baby to the uterus during pregnancy, placenta plays a vital role.

Here are some of the functions of placenta:

  • Produces hormones that help your baby grow.
  • Removes wastes and carbon dioxide from your baby.
  • Supply your baby oxygen and nutrients.
  • Passes immunity from your body to your baby.

As your blood flows through your uterus, the placenta seeps up immune molecules,  nutrients and oxygen circulating through your system. Through the umbilical cord, it shuttles these across the amniotic sac to your baby and into the blood vessels of the unborn.

The placenta acts as a barrier. It makes sure that the germs in your body do not make your baby sick. It keeps the bacteria and virus out of the womb. It prevents your baby’s cells from entering your bloodstream, to prevent setting off alarms.

How To Keep Your Placenta Healthy During Pregnancy?

Maintaining a healthy placenta is a must for foetal development and a healthy pregnancy. Mums can consume nutrient-rich calories, containing a large number of nourishing vitamins and minerals.

Lots of iron-rich foods is advisable as the baby absorbs large amounts of iron from the maternal blood. It will help prevent conditions such as iron-deficiency anaemia.

Include iron-rich food and green vegetables in your diet to maintain a healthy placenta. | Image Source: freepik

Studies have found eggs, nuts, yoghurt, green vegetables and sweet potatoes to be a must during pregnancy to maintain a healthy placenta.

Placental Grading

Placental grading or Grannum classification refers to an ultrasound grading system of the placenta based on its maturity. It determines the extent of calcification with the gestational age.

Grade 0:

The gestational week is less than 18 weeks.

  • The placental substance is a uniform echotexture without echogenic areas
  • There are no base layer echogenicities
  • The chorionic plate is smooth and well-defined.

Grade 1:

The gestational age is between 18-29 weeks.

  • This grade is considered as the early stage of placenta maturation.
  • The placental substance may contain a few echogenic areas that are randomly scattered.

Grade 2:

The gestational age is beyond 30 weeks.

  • The placental substance has linear echogenic densities which are incompletely divided.
  • Larger configurations are present in the basal plate.
  • The chorionic plate has more marked indentations.

Grade 3:

The gestational week is beyond 39 weeks.

  • The placenta is fully matured and the chorionic plate has complete indentations.
  • The basal layer is dense and bigger
  • The placental substance is divided into compartments, demarcating the cotyledons.

Complications Related To Placenta

Complications and abnormalities of placenta are not common in all pregnancies. These are usually detected through routine tests at your medical appointments or a diagnosis of physical symptoms. Some of these are:

  1. Placental insufficiency: Placental insufficiency refers to the failure of the placenta to provide enough nutrients to the foetus. This can happen if the placenta is unable to grow or function properly.

Placental insufficiency can result in low birth weight.

  1. Infarcts in the placenta: Infarcts are the areas of dead tissue within the placenta. It results in reduced blood flow in those areas. 

Although infarcts in the placenta do not not affect the unborn baby, the reduced blood flow in the placenta (especially expecting mums with hypertension) causes poor growth and even death of the unborn baby.

  1. Placental abruption: Placental abruption refers to a condition where a part of the placenta separates from the uterus. If the placenta detaches, these blood vessels break, resulting in heavy bleeding.

  1. Enlarged placenta: An enlarged placenta means that the placenta is either thicker than it should be or weighs more than your doctor thinks it should (or both).

Diabetes, smoking and an infection in the uterus are some of the causes of enlarged placenta.

  1. Anterior placenta: Although an anterior placenta does not have a negative impact on the birth process, you might not be able to feel your baby’s kicks easily. It could also make amniocentesis more challenging.

  1. Placenta previa: When the placenta is covering the cervix completely, it becomes difficult to deliver the baby vaginally and a caesarean section delivery is required. It can also cause major bleeding.

  1. Placenta accreta: Placenta accreta can occur during pregnancy when the placenta attaches deeply into the wall of the uterus. 

Women who have had caesarean sections, other placenta disorders or a history of tumour removal in the uterus are at an increased risk of this condition and it can be life-threatening.

How To Lower The Risk of Placental Problems?

Here are some of the tips to lower the risk of placental problems:

  • Do not miss any appointments and visit your doctor regularly throughout your pregnancy.
  • Discuss with your doctor to manage health conditions such as high blood pressure that can cause placental problems.
  • You can talk with your doctor about the potential risks before deciding to pursue an elective C-section.
  • Quit smoking and using drugs.
  • If you have had previous caesarean sections and have a low lying placenta, you can talk to your doctor about the risks of placenta accreta.
  • Exercise regularly during pregnancy after consulting a doctor to avoid placental insufficiency.
  • Consume iron-rich foods.
  • Avoid consuming sweetened items as women diagnosed with diabetes are at an increased risk of placental insufficiency.

Some Important Facts about Placenta

Here are some important facts about placenta:

  • The placenta is not a maternal organ. Genetically, it is half from the mum and half from the father.
  • It acts as a gland that secretes hormones during pregnancy which play a key role in supporting your baby.
  • It produces a hormone that stops the production of breast milk. After delivery, the mum’s body gets the signal that it is time to produce milk.
  • It is the only disposable organ as it is delivered after the birth of the baby.
  • Mums carry stem cells from their babies. As stem cells from babies can cross the placenta, a tiny number of cells can be found in a mum’s skin, organs and bone marrow.
  • A placenta is usually one-sixth of the unborn baby’s weight. It has a thickness that corresponds roughly to the baby’s gestational age. For example, a foetus that’s 20 weeks along would be nurtured by a placenta about 20 millimetres thick.
  • It has a unique ability to grow and infiltrate the mum’s body without being attacked by the mum’s immune system.
  • The blood of the mum and the baby pass through separate arteries of the placenta and do not mix.


  • When does the placenta form?

The placenta forms after a fertilised egg implants in your uterus around seven to 10 days after conception. It grows throughout your pregnancy to support your baby.

  • What happens to placenta after birth?

The placenta is delivered after childbirth, usually about five to 30 minutes after your baby is born. This is also called the third stage of labour. You would have to give one more push to deliver the placenta.

  • What happens if the placenta is not removed after birth?

If your placenta is not delivered, it can cause life-threatening bleeding and you can even develop an infection.

  • Which position of placenta is best for normal delivery?

Posterior placenta is considered to be the best for normal delivery. This is so because it allows the baby to grow, descend to the right position and align in the birth canal.

The placenta is an incredible life-giving organ and plays an important role in supporting the unborn throughout pregnancy. It is said that a healthy placenta is the reason for a healthy baby. Aptly so.  



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