Low-lying placenta (Placenta previa)
Fast facts
- A low-lying placenta happens during pregnancy, when the placenta develops low down in the uterus.
- Most cases of low-lying placenta are found during routine ultrasounds that are performed during the second trimester of pregnancy.
- Most women who are diagnosed with a low-lying placenta early in pregnancy have no problems later in the pregnancy, as the placenta moves up higher into the uterus and away from the cervix.
- For some women, the placenta remains low-lying during the weeks leading to labor. In these cases, the mother and baby will be more closely monitored; a caesarean delivery may be planned to prevent the danger of complications to the mother and baby.
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Cervix
The lower part of the uterus, leading out into the vagina.
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Labor
Signals the end of a pregnancy and the process of giving birth to a baby from the uterus to the outside world.
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Trimester
One third of a period of time. Often used to describe the three stages of pregnancy, in which each trimester is about three months long.
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Uterus
The hollow organ of the female reproductive system that is responsible for the development of the embryo and fetus during pregnancy. Also known as the womb.
What is a low-lying placenta?
The placenta is the organ that develops on the lining of the uterus (womb) when a woman becomes pregnant. The placenta is attached to the fetus by the umbilical cord.
The placenta serves many important functions during pregnancy, including:
- It produces hormones that help and direct fetal growth and development;
- It protects the fetus against bacterial infections, and;
- It is where the mother's blood supply and the fetal blood supply meet - oxygen and nutrients pass from the mother to the fetus, and waste products pass the other way.
The placenta attaches to the site where the fertilized egg implants into the lining of the uterus. In most cases, the placenta attaches towards the upper part of the uterus, away from the cervix, which is the opening through which the baby passes during delivery. In some pregnancies, the placenta instead attaches to a lower part of the uterus, but as the uterus continues to grow and expand, the placenta often moves higher into the uterus.
If the placenta is still lying low in the uterus by the 20th week of pregnancy, it is called a low-lying placenta or placenta praevia. There are a few types of low-lying placenta; some types may partially or even completely block the cervical opening.
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Cervix
The lower part of the uterus, leading out into the vagina.
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Fetus
An unborn human, from the ninth week of pregnancy until birth.
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Nutrients
Substances in foods that are necessary for the body to function and grow. They include macronutrients, which provide energy and micronutrients, which are substances needed in small amounts such as vitamins, minerals and trace elements.
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Umbilical cord
Also called the birth cord. A tube connecting the blood supply of the uterus of the mother to the circulatory system of the developing baby.
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Uterus
The hollow organ of the female reproductive system that is responsible for the development of the embryo and fetus during pregnancy. Also known as the womb.
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Cervical
Relating to the cervix, which is the lower part of the uterus that leads into the vagina.
Signs and symptoms
Many women may not experience any symptoms with a low-lying placenta. For women who do experience symptoms, these may include:
Vaginal bleeding
Vaginal bleeding may be experienced during the second half of pregnancy. The bleeding is usually painless and may stop without treatment, only to return days or weeks later. The bleeding can range from light to heavy.
Blood loss
Some women may experience severe enough blood loss that it causes anemia. Symptoms of anemia include pale skin, a fast, weak pulse and breathlessness.
Symptoms associated with early labor
Some women may experience symptoms often associated with labor, such as regular contractions and aches or pains in the lower abdomen.
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Abdomen
The part of the body that lies between the chest and the pelvis.
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Anemia
A deficiency in red blood cells or hemoglobin in the body.
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Labor
Signals the end of a pregnancy and the process of giving birth to a baby from the uterus to the outside world.
Causes and Risk factors
It is not clear why some women develop a low-lying placenta, but there are factors that are known to increase the risk. These include:
- Smoking;
- Being over the age of 35;
- A previous pregnancy;
- Being pregnant with more than one baby i.e., twins/triplets;
- A previous caesarean section;
- Have previously had low-lying placenta, and;
- Cocaine use.
Types
There are three main types of low-lying placentas. They are classified by their position in the uterus:
- Low-lying placenta praevia - the placenta is located close to the cervical opening without covering it;
- Partial or marginal placenta praevia - the placenta partially blocks the cervical opening, and;
- Complete placenta praevia - the placenta covers and blocks the cervical opening.
The various positions of low-lying placenta.
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Uterus
The hollow organ of the female reproductive system that is responsible for the development of the embryo and fetus during pregnancy. Also known as the womb.
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Cervical
Relating to the cervix, which is the lower part of the uterus that leads into the vagina.
Methods for diagnosis
Ultrasound
Most cases of low-lying placenta are found during routine ultrasounds that are performed during the second trimester of pregnancy.
Some cases of low-lying placenta may require more scans, to more accurately confirm the position of the placenta. A popular scan for diagnosing a low-lying placenta is a transvaginal ultrasound, in which your doctor inserts a wand-like ultrasound device into the vagina to better see the placenta.
Physical examination
Your doctor may also perform a physical examination in order to determine the position of the baby within the uterus, because in some cases of placenta praevia, the baby may be positioned sideways or bottom-first. The position of the baby may affect whether a vaginal birth is possible.
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Trimester
One third of a period of time. Often used to describe the three stages of pregnancy, in which each trimester is about three months long.
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Uterus
The hollow organ of the female reproductive system that is responsible for the development of the embryo and fetus during pregnancy. Also known as the womb.
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Transvaginal ultrasound
An internal ultrasound of the female pelvis. An ultrasound probe is inserted into the vagina to get more detailed views of the inside of the pelvis.
Types of treatment
The type of treatment required for a low-lying placenta may vary depending on the:
- Amount of bleeding;
- Stage of pregnancy;
- Health of the mother and baby, and;
- Position of the baby and placenta.
Further ultrasound scans are performed later in pregnancy to confirm the position of the placenta. In cases where the placenta is blocking the cervix, vaginal delivery will not be possible and a caesarean section will need to be scheduled.
- Women who experience mild vaginal bleeding may not require hospitalization and may be advised to get plenty of rest at home. You may be advised by your doctor to avoid sexual activity or heavy strenuous activity.
- If the bleeding is more serious, the baby and mother may be monitored, either during a hospital stay or at home. In these cases, a vaginal delivery may still be possible, although some women may need to undergo a caesarean section.
- Women with very heavy bleeding may need to remain in hospital, with more severe cases requiring blood transfusion and medication to prevent preterm (before 37 weeks) labor. Women who experience more severe symptoms and whose cervix is blocked usually undergo caesarean delivery.
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Cervix
The lower part of the uterus, leading out into the vagina.
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Labor
Signals the end of a pregnancy and the process of giving birth to a baby from the uterus to the outside world.
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Preterm
A baby that is born before 37 weeks' gestation.
Potential complications
There may be some complications associated with having a low-lying placenta. The complications can affect either the mother or her baby, and may vary depending on the:
- Position of the placenta;
- Stage of the pregnancy;
- Health of the mother and baby;
- Amount of vaginal bleeding, and;
- Position of the baby within the uterus.
Potential complications for the mother
Hysterectomy
Women with low-lying placenta who have previously undergone a caesarean section may have scar tissue on their uterine walls that puts them at an increased risk of developing:
- Placenta accrete - in which the placenta remains firmly attached to the uterus;
- Placenta increta - in which the placenta has grown into the uterus, or;
- Placenta percreta - in which the placenta has grown through the uterus.
Such conditions may be confirmed by using computerized tomography (CT) or magnetic resonance imaging (MRI) scans. The treatment usually involves a hysterectomy after the baby has been delivered, as the placenta cannot be separated from the uterus.
Heavy bleeding
Some women with low-lying placenta may experience particularly heavy bleeding during labor, or after the baby has been delivered. If blood loss is severe enough, a blood transfusion may be required.
Placental abruption
Women with low-lying placenta have an increased risk of developing a placental abruption, in which the placenta separates partially or even fully from the wall of the uterus. Depending on the degree of abruption, some women may experience severe blood loss and require a blood transfusion. Severe cases can cause shock, affect other organs of the body and increase the risk of death.
Postpartum endometritis
Some women may be at an increased risk of developing an infection of the inner lining of their uterus, called postpartum endometritis.
Potential complications for the baby
Depending on the health of the baby and the degree of distress, blood loss and lack of oxygen that they may have experienced before, during and after labor, some complications may include:
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Anemia
A deficiency in red blood cells or hemoglobin in the body.
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Congenital malformation
A physical defect that is present at birth.
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Computerized tomography
A scan that uses X-rays to create a 3D image of the body. This can detect abnormalities more effectively than a simple X-ray can.
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Hysterectomy
Hysterectomy is the surgical removal of a woman's uterus (womb). A total hysterectomy involves removal of the uterus and cervix.
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Infection
Entry into the body of microorganisms that can reproduce and cause disease.
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Labor
Signals the end of a pregnancy and the process of giving birth to a baby from the uterus to the outside world.
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MRI
A type of imaging that uses a magnetic field and low-energy radio waves, instead of X-rays, to obtain images of organs.
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Shock
A life-threatening condition in which the organs and other tissues do not receive adequate blood flow.
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Uterus
The hollow organ of the female reproductive system that is responsible for the development of the embryo and fetus during pregnancy. Also known as the womb.
Prognosis
Most women who are diagnosed with a low-lying placenta early in pregnancy have no problems later in the pregnancy, as the placenta moves up higher into the uterus and away from the cervix. Some women whose low-lying placenta persists into their third trimester will go on to a preterm delivery.
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Cervix
The lower part of the uterus, leading out into the vagina.
X
Trimester
One third of a period of time. Often used to describe the three stages of pregnancy, in which each trimester is about three months long.
X
Uterus
The hollow organ of the female reproductive system that is responsible for the development of the embryo and fetus during pregnancy. Also known as the womb.
X
Preterm
A baby that is born before 37 weeks' gestation.
Prevention
Although the reasons why some women develop a low-lying placenta during their pregnancy are not clearly understood, getting good prenatal care may help identify complications early on. In addition, the chances of developing a low-lying placenta may be reduced by avoiding the known risk factors.
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Prenatal
Before the birth of a baby.
References
- Placenta Praevia. Accessed August 19 2014. link here
- What Is the Placenta? - Health Questions - NHS Choices September 12 2013. link here
- What Is the Placenta? - Health Questions - NHS Choices September 12 2013. link here
- Low Lying Placenta - What It Means To Have Low Lying Placenta. Accessed August 19 2014. link here
- Placenta Previa. BabyCenter. Accessed August 19 2014. link here Placenta Previa. Accessed August 19 2014. link here
- Placenta Previa Causes Symptoms Treatments. Accessed August 19 2014. link here
- Placenta Previa Symptoms - Diseases and Conditions - Mayo Clinic. Accessed August 19 2014. link here
- Placenta Previa Treatments and Drugs - Diseases and Conditions - Mayo Clinic. Accessed August 19 2014. link here
- Placenta Previa-Topic Overview. Accessed August 19 2014.
- link here
- Understanding Placenta Previa -- Treatment. Accessed August 19 2014.
- link here
10 Most frequently asked questions (FAQs)
What is a low-lying placenta? When the placenta attaches to the wall of the uterus during early pregnancy, it may be positioned lower in the uterus. As the uterus expands throughout the pregnancy, the placenta will often move higher up in the uterus, away from the cervical opening. If the placenta is still lying low in the uterus by the 20th week of pregnancy, it is called a low-lying placenta or placenta praevia. What are the symptoms of a low-lying placenta? Many women with a low-lying placenta may not experience any symptoms. If symptoms do occur, these may include vaginal bleeding, which occurs during the second half of pregnancy. Some women may experience symptoms often associated with labor including regular contractions and aches or pains in the lower abdomen. How is low-lying placenta treated? The treatment of low-lying placenta may vary depending on the amount of bleeding, stage of pregnancy, health of mother and baby, and position of the baby and placenta. You may be advised to avoid sexual activity or heavy strenuous activity. In case of serious bleeding, a hospital stay may be advised. Can low-lying placenta be prevented? Although the reasons why some women develop a low-lying placenta during their pregnancy are not clearly understood, getting good prenatal care may help identify complications early on. Avoiding known risk factors, such as smoking and cocaine use, may also reduce the chances of developing a low-lying placenta. Are there different types of low-lying placenta? There are three main types of low-lying placenta. They are classified by their position in the uterus: 1) Low-lying placenta praevia - the placenta is located close to the cervical opening without covering it. 2) Partial or marginal placenta praevia - the placenta partially blocks the cervical opening. 3) Complete placenta praevia - the placenta covers and blocks the cervical opening. What is the outcome for low-lying placenta? Most women who are diagnosed with a low-lying placenta early in pregnancy will not develop problems later in the pregnancy, as their placenta will move up higher into the uterus and away from the cervix. Some women whose low-lying placenta persists into their third trimester will go on to a preterm delivery. Is low-lying placenta serious? Most cases of low-lying placenta resolve on their own as the uterus continues to expand. However, there are risks of developing placental abruption, where the placenta becomes partially or even fully detached from the uterine wall. Depending on the extent of abruption, there may be blood loss that may require hospitalization and a blood transfusion. If the placenta is low-lying during late pregnancy, there may be serious birthing problems as the cervical opening is blocked by the placenta. What increases the chances of developing low-lying placenta? Although the exact cause of low-lying placenta is not clearly understood, there are some factors that may increase its likelihood, including: smoking; being over the age of 35; a previous pregnancy; being pregnant with more than one baby i.e., twins/triplets; previous caesarean section; having previously had low-lying placenta, and; cocaine use.
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