Placenta previa is a medical condition that occurs during pregnancy when the placenta covers the cervix during growth. In some instances only a portion of the cervix is covered, whereas in other cases the entire cervix is closed by placenta. Placenta previa is rare, affecting around 1 in every 200 pregnancies. If left undiagnosed and untreated, however, it can lead to birth injuries and health problems for both mother and baby.
Placenta Previa Causes
During pregnancy, a woman’s placenta maneuvers around to accommodate a growing womb and infant. During early pregnancy, the placenta typically lies low, and as the womb increases in size, it moves to the top portion of the womb. In fact, towards the end of the pregnancy and by the third trimester, the placenta should be at the top of the wound, away from the cervix, in preparation for the upcoming birth. Women with placenta previa, however, will experience a full, partial, or marginal cervix blockage due to the placenta moving towards the bottom of the womb.
In many cases, placenta previa is caused by uterine factors. For example, scarring of the lining tissue of the uterus can occur from previous cesarean section (C-section) deliveries, D&C procedures, or abortions. The scarring heightens the risk of women having placenta previa.
Another cause of placenta previa involves placental issues. Carrying more than one baby, smoking cigarettes, and living in an area with a higher altitude can cause the placenta to grow larger than normal in order to compensate. As a result, a larger placenta may move towards the bottom of the womb.
Other risks factors include:
- Maternal age of 35 and older
- Prior pregnancies with placenta previa
- Prior births, with or without placenta previa
- Multiple induced abortions
- Maternal diabetes
Different Types of Placenta Previa
Marginal: Marginal placenta previa occurs when the placenta moves next to the cervix, but does not cover it
Partial: Partial placenta previa occurs when the placenta covers part of the cervix
Complete: Complete placenta previa occurs when the placenta covers the entire cervix
Placenta Previa Symptoms
The primary symptom associated with placenta previa is a sudden onset of vaginal bleeding, which may or may be accompanied by cramps. Bleeding will vary in severity according to each person. Some women may experience heavy bleeding while others may have light bleeding and in some cases, no bleeding at all. Additionally, the bleeding may stop for a weeks only return later. In some cases, bleeding doesn’t occur until labor starts and in other cases, it may occur after 20 weeks gestation.
Placenta Previa Treatment Options
Treatment options for placenta previa will greatly depend on the gestational age and the overall health of the infant, how severe the bleeding is and/or if it has stopped, and the position of both placenta and baby.
For complete placenta previa, a C-section delivery is almost always the only option. C-sections are typically scheduled after 36 weeks gestation, but it may be sooner if the bleeding is extreme and can’t be stopped.
For marginal and partial placenta previa, normal delivery may still be an option, but will depend on the extent of bleeding, and in partial placental previa, how much of the cervix is blocked. Reducing activities and extended bed rest are almost always recommended in these cases.
Other treatment options may include:
- Blood transfusions
- Medications that help sustain a pregnancy until 36 weeks gestation
- Steroid shots to help the baby’s lungs mature
- Rhogam shots for Rh negative blood types
Placenta Previa Prognosis
The most serious risk associated with placenta previa is severe, uncontrollable bleeding. When this occurs, infants may need to be delivered before their vital organs have developed, putting them at risk for a myriad of life-threatening health issues.
Physicians should always monitor pregnant women closely who have the risk factors associated with placenta previa. Early detection and diagnosis may help the bleeding from getting too severe. In fact, when physicians do or fail to do the following actions, both mother and infant are at risk for health problems:
- Failure to monitor an infant after placenta previa has been diagnosed, which can lead to fetal hypoxia
- Failure to conduct ultrasounds and formulate a correct plan of action for mothers with placenta previa
- Attempting a normal delivery when complete placenta previa is present
- Delaying a scheduled C-section
Placenta Previa Health Risks and Complications
Health risks for infants may include:
- Preterm birth
- Congenital abnormalities
- Respiratory Distress Syndrome
- Low birth weight
- Stillborn birth
Maternal Risks include: