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These kinds of placental problems are some of the most common complications of the second half of pregnancy.
What is placental abruption?
Placental abruption (sometimes called abruptio placentae) is a condition in which the placenta peels away from the uterine wall, partially or almost completely, before birth. Mild cases may cause few problems, but severe cases can deprive the baby of oxygen and nutrients. Severe cases also can cause bleeding in the mother that can be dangerous to her and the baby.
Placental abruption increases the risk of premature birth (birth before 37 completed weeks of pregnancy). Studies suggest that abruption contributes to about 10 percent of premature births (1). Premature babies are at increased risk for health problems during the newborn period, lasting disabilities and even death. Abruption also increases the risk for poor fetal growth and stillbirth (1).
How common is placental abruption?
Abruption occurs in about 1 in 100 pregnancies (2). It occurs most often in the third trimester, but it can happen any time after about 20 weeks of pregnancy.
What are the symptoms of abruption?
The main symptom of placental abruption is vaginal bleeding. If a pregnant woman has vaginal bleeding, she should contact her health care provider. She also may have uterine discomfort and tenderness or sudden, continuous abdominal pain. In a few cases, these symptoms may occur without vaginal bleeding because the blood is trapped behind the placenta.
How is placental abruption diagnosed?
If a provider thinks a woman is having an abruption, he may recommend that the woman go to the hospital for a complete evaluation. The woman gets a physical exam and, most likely, an abdominal ultrasound. An ultrasound can detect many, but not all, cases of abruption.
How is placental abruption treated?
A woman’s treatment depends on the severity of the abruption and her baby’s gestational age (weeks of pregnancy). A mild abruption usually is not dangerous. If a woman has a mild abruption at or near term (37 to 41 weeks), her provider may recommend immediate delivery by inducing labor or cesarean birth (c-section). Giving birth immediately can help avoid risks associated with the abruption getting worse.
If a woman has a mild abruption and her baby is between 24 and 34 weeks gestation, she may be admitted to the hospital for careful monitoring. If tests show that mother and baby are doing well, the provider may try to prolong the pregnancy to avoid prematurity-related complications for the baby. Some women may be able to go home after treatment, while others may need to stay in the hospital until they give birth (1, 3). If the woman needs to give birth immediately, her provider may recommend treatment with drugs called corticosteroids. These drugs help the baby’s lungs mature and reduce the risk of prematurity-related complications and infant death.
A woman may need to give birth immediately, often by c-section, if:
What causes placental abruption?
The cause of abruption is unknown. However, the following factors can increase a woman’s risk for abruption (1, 3, 4):
One study suggests that women who are underweight may be at increased risk of abruption (5). Underweight is defined as a body mass index (BMI) of less than 18.5, which is weight less than 110 pounds for a 5’4” woman. Underweight women in the study who gained the recommended amount of weight during pregnancy (usually 28 to 40 pounds for underweight women) reduced their risk.
What is the risk of an abruption happening again in another pregnancy?
A woman who has had an abruption has about a 10-percent chance of it happening again in a later pregnancy (1).
What can a woman do to reduce her risk for abruption?
In most cases, abruption cannot be prevented. However, a woman can help reduce her risk by:
What is placenta previa?
Placenta previa is a low-lying placenta that covers part or all of the opening of the cervix. This position can block the baby’s exit from the uterus. As the cervix begins to thin and dilate (open up) in preparation for labor, blood vessels that connect the placenta to the uterus may tear and cause bleeding. During labor and birth, bleeding can be severe, which can be dangerous to mother and baby.
As with placental abruption, placenta previa can result in the birth of a premature baby.
How common is placenta previa?
Placenta previa occurs in about 1 in 200 pregnancies (6).
What are the symptoms of placenta previa?
The most common symptom of placenta previa is painless uterine bleeding during the second half of pregnancy. Women who experience vaginal bleeding in pregnancy should contact their provider.
How is placenta previa diagnosed?
An abdominal ultrasound usually can diagnose placenta previa and pinpoint the placenta’s location. In some cases, providers may use a vaginal ultrasound to confirm the diagnosis (3, 7). If the provider suspects placenta previa, he may not do a vaginal examination with his gloved finger because it can cause heavy bleeding.
Some women who have no vaginal bleeding learn during a routine ultrasound that they have a low-lying placenta. A pregnant woman should not be too worried if this happens, especially if she is in the first half of pregnancy. More than 90 percent of the time, placenta previa diagnosed in the second trimester corrects itself by term (3, 6).
How is placenta previa treated?
Treatment depends on the baby’s gestational age, the severity of the bleeding and the condition of mother and baby. The treatment goal is to keep the woman pregnant as long as possible until the baby is at or near term. Providers recommend cesarean birth for nearly all women with placenta previa because it often can prevent severe bleeding.
When a woman develops significant bleeding due to placenta previa at about 34 to 36 weeks of pregnancy, her provider may recommend an immediate c-section (3).
Women who develop bleeding as a result of placenta previa before about 34 weeks generally are admitted to the hospital where they can be monitored closely. If tests show that mother and baby are doing well, the provider may attempt to prolong the pregnancy. If a woman has a significant amount of bleeding, she may be treated with blood transfusions. She also may be treated with corticosteroid drugs to help prevent prematurity-related complications in the baby.
Some women can go home after bleeding stops, but others must remain in the hospital until they give birth.
At 36 to 37 weeks, the provider may suggest an amniocentesis to test the amniotic fluid around the baby to see if the baby’s lungs are mature. If they are mature, the provider may recommend an immediate c-section to prevent risks associated with future bleeding.
At any stage of pregnancy, a c-section may be necessary if the mother develops dangerously heavy bleeding or if the mother or baby is having difficulties.
What causes placenta previa?
The cause of placenta previa is unknown. However, certain factors can increase a woman’s risk (3, 6, 7):
What is the risk of placenta previa happening again in another pregnancy?
A woman who has had a placenta previa in a previous pregnancy has a 2- to 3-percent chance of having it in another pregnancy (3).
Can a woman reduce her risk for placenta previa?
There is no known way to prevent placenta previa. However, a woman may be able to reduce her risk by avoiding using cigarettes and cocaine. She also may be able to reduce her risk in future pregnancies by not having an elective c-section (one that is scheduled for convenience) unless there is a medical reason. Studies suggest that a woman’s risk of placenta previa increase with each cesarean birth (8).
What is placenta accreta?
Placenta accreta is a placenta that implants too deeply and too firmly into the uterine wall. Similarly, placenta increta and percreta are placentas that imbed themselves even more deeply into uterine muscle or through the entire thickness of the uterus, sometimes extending into nearby structures, such as the bladder. The abnormal implantation of the placenta is likely to occur at the site of a uterine scar from prior surgery or c-section.
In these disorders, the placenta does not completely separate from the uterus after a woman gives birth. This can lead to dangerous bleeding.
How common are placenta accreta and related disorders?
These disorders occur in up to 1 in 530 births (9). The rates of these conditions are increasing, largely due to the rising rate of c-sections (9, 10). Placenta accreta and related disorders sometimes lead to premature birth.
What are the symptoms of placenta accreta and related disorders?
Like placenta previa, these disorders often cause vaginal bleeding in the third trimester.
Who is at risk for placenta accreta and related disorders?
These disorders occur most often in women who have placenta previa in the current pregnancy and who have had one or more c-sections or other uterine surgeries (6, 10).
How are placenta accreta and related disorders diagnosed?
These disorders can be diagnosed with an abdominal or vaginal ultrasound. In some cases, another imaging technique called magnetic resonance imaging (MRI) may be recommended.
How are placenta accreta and related disorders treated?
When placenta accreta is diagnosed before birth, the provider may recommend a c-section immediately followed by a hysterectomy (surgical removal of the uterus). This approach appears to reduce blood loss and complications in the mother (10, 11). The provider may recommend that the woman give birth at around 34 to 35 weeks of pregnancy to help prevent dangerous bleeding (10, 11). If a woman wants to have future pregnancies, the provider may perform certain surgical procedures before the c-section to try to control bleeding and save the uterus (9, 11).
When placenta accreta is diagnosed at birth, the provider may try to surgically remove the placenta in order to stop the bleeding. However, a hysterectomy is often necessary (11).
What are some other placental problems?
In some cases, the placenta does not develop correctly or function as well as it should. It may be too thin, too thick or have an extra lobe, or the umbilical cord may not be attached correctly. Problems can occur during pregnancy that damage the placenta, including infections, blood clots and infarcts, which is an area where tissue is destroyed.
These placental abnormalities can contribute to a number of complications, such as:
The provider often examines the placenta after a woman gives birth. In some cases, the provider sends the placenta to be tested in a lab, especially if the newborn has certain complications, such as poor growth.
Does the March of Dimes support research on placental conditions?
A number of March of Dimes grantees are exploring how certain genes regulate development and function of the placenta. This research could lead to ways to help prevent placental conditions and complications that result from them, including miscarriage, growth problems and premature birth.
One grantee is studying possible placental blood vessel abnormalities in women with inherited blood-clotting disorders (thrombophilias). This grantee hopes to develop treatments to prevent pregnancy complications, which may be more common in affected women.