During pregnancy, the placenta, which normally lies near the top of the placenta, provides all essential nutrients to the baby and serves as a filtering mechanism for waste products. In a small number of pregnancies, the placenta is determined to be in a “low lying” position, but, in most cases, will move upwards toward the top of the uterus before delivery. In rare cases, however, the placenta moves and remains downward and implants itself in the lower region of the uterus, either partially or fully covering the opening of the birth canal. This is known as placenta previa. When this happens, the position of the placenta can cause hemorrhaging, which can endanger the well-being of both the mother and baby.
The three types of placenta previa are as follows:
Marginal Previa – a condition in which the edge of the placenta is near the cervical opening. This condition poses a risk of hemorrhage during labor and delivery, because, as the cervix dilates, the placenta can move and partially block the opening of the birth canal and, as such Cesarean section is often the standard course of delivery.- Partial Previa – a condition characterized by the placenta partially covering the cervical opening. Cesarean section is often the recommended method of delivery, as pressure from the baby during a vaginal delivery can compromise the placenta and pose a risk for hemorrhage.
- Total Previa – the most severe form of previa, in which the placenta has moved downward and completely covers the cervical opening. Cesarean section is the only safe course of delivery.
Although in some cases, placenta previa yields no symptoms at all, the primary symptom is the sudden onset of spotting or bright red vaginal bleeding in the second or third trimester, most often unaccompanied by pain or cramping.
Risk for developing placenta previa increase with the following:
Previous experience with placenta previa
Scarring of the lining of the uterus (from previous Cesarean sections, uterine surgeries, D and C procedures following miscarriage, etc.)
Multiple pregnancy (twins or higher)
Increased number of pregnancies
Smoking
Advanced maternal age
Previous cesarean section
History of elective abortion
Potential Complications
Risks to a baby affected by placenta previa may include:
Risks to a baby affected by placenta previa may include:
Acute fetal blood loss;
Intrauterine growth retardation, as a result of the inability of the poorly-positioned placenta to provide adequate nourishment to the fetus;
Possible increased risk of congenital abnormalities.
Risks for the mother include:
- Moderate to life-threatening hemorrhage.
- Increased risk of postpartum hemorrhage
- Increased risk of placenta accreta, a condition in which the placenta attaches directly to the uterine wall.
- Cesarean section delivery.
Treatment
The course of treatment varies, depending on the severity of the condition, the gestational stage and/or potential viability of the fetus, and the amount of uterine bleeding present. An ultrasound may be performed to determine the exact location of the placenta and, if absolutely necessary, a vaginal exam may be required. In severe cases of previa, if a vaginal exam is proved to be a necessity, it is often done in an operating room, as the exam itself can lead to hemorrhage and necessitate an emergency Cesarean section.
To avoid the risk of very premature deliveries, medication may be given to prevent labor with a goal of prolonging the pregnancy to at least 36 weeks. In severe cases, fetal blood loss or hemorrhage may occur, presenting the immediate need for immediate delivery. Other courses of treatment include modified or complete bed rest either at home or in medical facility, recommendations to avoid intercourse and/or strenuous activity, and, in some cases, amniocentesis to evaluate the maturity of the baby’s lungs in case an emergency Cesarean section is warranted. If the condition is severe and delivery appears to be imminent, steroid medications may be administered to expedite maturation of the fetal lungs. In any case, Cesarean section appears to be the most prudent approach to delivery in many previa-affected pregnancies.
Though placenta previa once posed a serious risk to both mother and baby, some statistics today show that, as a result of medical technology and advanced obstetrical and neonatal care, nearly 99% of those affected will experience an excellent prognosis. The prognosis for the term baby is particularly favorable, although that of a premature infant will depend on the gestational age at delivery as well the overall condition of the infant.
Placenta previa, although a rare condition that is estimated to affect less than 1% of pregnancies, can pose serious risks to both mother and baby if left untreated. As such, any vaginal bleeding in the second and third trimesters should be immediately reported to a medical practitioner.
The course of treatment varies, depending on the severity of the condition, the gestational stage and/or potential viability of the fetus, and the amount of uterine bleeding present. An ultrasound may be performed to determine the exact location of the placenta and, if absolutely necessary, a vaginal exam may be required. In severe cases of previa, if a vaginal exam is proved to be a necessity, it is often done in an operating room, as the exam itself can lead to hemorrhage and necessitate an emergency Cesarean section.
To avoid the risk of very premature deliveries, medication may be given to prevent labor with a goal of prolonging the pregnancy to at least 36 weeks. In severe cases, fetal blood loss or hemorrhage may occur, presenting the immediate need for immediate delivery. Other courses of treatment include modified or complete bed rest either at home or in medical facility, recommendations to avoid intercourse and/or strenuous activity, and, in some cases, amniocentesis to evaluate the maturity of the baby’s lungs in case an emergency Cesarean section is warranted. If the condition is severe and delivery appears to be imminent, steroid medications may be administered to expedite maturation of the fetal lungs. In any case, Cesarean section appears to be the most prudent approach to delivery in many previa-affected pregnancies.
Though placenta previa once posed a serious risk to both mother and baby, some statistics today show that, as a result of medical technology and advanced obstetrical and neonatal care, nearly 99% of those affected will experience an excellent prognosis. The prognosis for the term baby is particularly favorable, although that of a premature infant will depend on the gestational age at delivery as well the overall condition of the infant.
Placenta previa, although a rare condition that is estimated to affect less than 1% of pregnancies, can pose serious risks to both mother and baby if left untreated. As such, any vaginal bleeding in the second and third trimesters should be immediately reported to a medical practitioner.
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