What is the placenta?
The placenta is an organ that helps your baby grow and develop. It’s attached to the lining of the womb and is connected to your baby by the umbilical cord. The placenta passes oxygen, nutrients and antibodies from your blood supply to your baby. It also carries waste products from your baby to your blood supply, so your body can get rid of them.
The placenta develops in the first few weeks of pregnancy, wherever the fertilised egg embeds itself. This could be along the top, sides, front or back wall of the uterus.
What issues can affect the placenta?
An anterior placenta is when the placenta attaches to the front wall of the uterus. This is a normal place for the placenta to implant and develop and it is very unlikely to cause any complications.
Having an anterior placenta can make it a bit harder to feel your baby move because your baby is cushioned by the placenta lying at the front of your stomach.
Find out more about anterior placenta.
Chronic histiocytic intervillositis
Chronic histiocytic Intervillositis (CHI) is an extremely rare condition that may affect the placenta during pregnancy. In CHI, the mother’s immune system reacts abnormally to the pregnancy and causes damage to the placenta, increasing the risk of miscarriage and stillbirth.
Unfortunately, CHI has no symptoms and can only be diagnosed after pregnancy. Women with previous CHI will have extra treatment and care in any future pregnancies to help prevent any problems.
Find out more about chronic histiocytic intervillositis.
Fetal growth restriction
Fetal growth restriction (FGR) is a condition in which a baby's growth slows or stops during pregnancy. Most cases of FGR are caused by failure of the placenta but there are also other factors, including intrauterine infection and smoking in pregnancy.
FGR happens in around 3% pregnancies.
Find out more about fetal growth restriction.
Low-lying placenta (also known as placenta praevia)
A low-lying placenta (also known as placenta praevia) is when the placenta attaches lower down and may cover a part of or all of the cervix (the entrance to the womb).
This can cause bleeding in pregnancy or during your baby’s birth, so you may need to give birth in the hospital. If the placenta is near or covering the cervix you won’t be able to deliver vaginally and will need a caesarean section.
Find out more about low-lying placenta.
Placental abruption is a serious condition in which the placenta starts to come away from the inside of the womb wall before the baby has delivered. This is an emergency because it means that the support system for the baby is failing.
Find out more about placental abruption.
Placenta accreta is when the placenta is attached and embedded too deeply into the wall of the uterus. This is a rare complication of pregnancy that makes it difficult to deliver the placenta after you give birth.
Find out more about placenta accreta.
After your baby is born, your womb will carry on contracting and the placenta is delivered. This is called the third stage of labour.
Sometimes the placenta or part of the placenta or membranes can remain in the womb. This is known as retained placenta. It isn’t very common, but a retained placenta can cause complications if it isn’t treated.
Find out more about retained placenta.
In most pregnancies, blood vessels from the umbilical cord insert directly into the placenta. In vasa praevia, these vessels are not protected by the umbilical cord or the placenta tissue. Instead, they go across the entrance to the birth canal, beneath the baby.
Vasa praevia is rare, but it can be dangerous because the blood that is lost comes from your baby.
Find out more about vasa praevia.
Tommy’s is the largest charity carrying out research into pregnancy loss and premature birth in the UK. We are funding various research projects that are focusing on the placenta and potential pregnancy complications. Find out more about our research.
NHS Choices. What is the placenta? https://www.nhs.uk/common-health-questions/pregnancy/what-is-the-placenta/ (Page last reviewed: 03/09/2018. Next review due: 03/09/2021)
Sharma D et al (2016) Intrauterine Growth Restriction: Antenatal and Postnatal Aspects. Clinical Medicine Insights: Pediatrics doi: 10.4137/CMPed.S40070 1
Royal College of Obstetricians and Gynaecologists (2019) Your baby's movements in pregnancy London RCOG https://www.rcog.org.uk/globalassets/documents/patients/patient-information-leaflets/pregnancy/pi-your-babys-movements-in-pregnancy.pdf
NHS Choices. What complications can affect the placenta? https://www.nhs.uk/common-health-questions/pregnancy/what-complications-can-affect-the-placenta/ (Page last reviewed: 26/09/2018. Next review due: 26/09/2021)
Royal College of Obstetricians and Gynaecologists (2018) Placenta praevia, placenta accreta and vasa praevia https://www.rcog.org.uk/globalassets/documents/patients/patient-information-leaflets/pregnancy/pi-placenta-praevia-placenta-accreta-and-vasa-praevia.pdf
[Oyelese Y and Ananth CV (2006) Placenta Abruption. Obstetrics and Gynecology. 2006 Oct;108(4):1005-16.
ℹLast reviewed on July 12th, 2019. Next review date July 12th, 2022.