Placenta Previa
- MedReport Foundation
- 1 day ago
- 3 min read
Written by Hannah Simpson, BSN, RN
Image from Freepik
What is Placenta Previa?
Placenta previa is a problem with the location of the placenta in pregnancy. The
placenta is the organ that provides oxygen and nutrition to the developing baby and
removes waste from the baby during pregnancy. Typically, the placenta is located at the
top or the side of the uterus. However, in placenta previa, the placenta covers all or
some of the cervix. This is a problem because the cervix is the opening to the birth
canal. When the placenta blocks part or all of the cervix, vaginal delivery can cause
life-threatening bleeding.
Types of Placenta Previa
Placenta previa can be marginal, partial, or complete. A marginal placenta previa is
located at the edge of the cervix. It comes into contact with the cervix, but it does not
block it. This type of placenta previa may resolve on its own before the woman’s due
date. This is because as the uterus expands, the placenta may shift upwards and no
longer interfere with the cervix. A partial placenta previa blocks part of the cervix. A
complete placenta previa covers the entire cervical opening.
Risk Factors
There are certain factors that make a woman more likely to have placenta previa during
her pregnancy. These factors include having previous pregnancies, previous c-section,
previous placenta previa, maternal age above 35, smoking, and cocaine use (1).
Symptoms
The primary symptom of placenta previa is bright red vaginal bleeding. Although it is
possible for women to experience cramping, it is more likely that the bleeding will be
without pain. The amount of bleeding can vary, but it is possible that enough bleeding
can occur that it can become life-threatening. The bleeding is most likely to begin in the
second half of pregnancy. It may be sporadic in nature. It may start, stop, and start
again after several days (2).
Health Risks for the Mother
Placenta previa poses certain risks to the health of the mother and the baby. Most of
the risks are either bleeding or complications of bleeding. The bleeding can occur
during pregnancy, and it can also occur during labor and delivery. A blood transfusion
may be necessary. A woman with placenta previa can bleed enough for it to be
life-threatening. Another risk is early delivery. If a woman with placenta previa begins
bleeding uncontrollably, she may require early delivery by c-section. Because of the
risk of blood loss, there is also a risk of anemia. Anemia means the woman’s blood
supply cannot carry enough oxygen to her body (3). This can cause dizziness,
shortness of breath, and fatigue.
Health Risks for the Baby
One of the health risks to the baby is premature birth. If the woman requires early
delivery due to severe bleeding, the baby may be born too early. This may lead to low
birth weight and difficulty breathing if the baby’s lungs are not fully developed at the
time of delivery (2).
Diagnosis and Treatment
Placenta previa is usually diagnosed in the second trimester by ultrasound. During
pregnancy, placenta previa is treated with pelvic rest (1). Pelvic rest means avoiding
putting anything into the vagina or performing any activity that would put stress on the
pelvic floor muscles. This is recommended because any manipulation of the placenta
can lead to severe bleeding (4). This means avoiding sexual intercourse, douching,
and tampons. Depending on the position of the placenta, bed rest may also be
indicated. If a substantial amount of bleeding occurs, a blood transfusion may be
necessary. Placenta previa nearly always requires a c-section delivery (2). This is
because of the risk of severe bleeding during vaginal delivery when the placenta is
partially or completely covering the cervix. The bleeding can be severe enough to
threaten the life of the mother and the baby. A c-section is usually scheduled electively
at 36-37 weeks. If a woman with placenta previa starts bleeding severely during
pregnancy, she may require an emergency c-section.
Conclusion
Placenta previa is a condition where the placenta is not in the right place in the uterus.
Instead of being at the top or the side of the uterus, it is partially or completely covering
the cervix. This means that vaginal delivery can cause severe bleeding and a c-section
is likely required. During pregnancy, management involves avoiding activities that can
cause bleeding. This is accomplished by pelvic rest and potentially bed rest. Always
consult a healthcare provider for concerns regarding the care and treatment of placenta
previa.
References
1. Placenta previa: MedlinePlus Medical Encyclopedia. Available from:
2. Cleveland Clinic. Placenta Previa: Symptoms, Causes & Treatments. Available
3. Anemia: MedlinePlus Medical Encyclopedia. Available from:
4. Anderson-Bagga FM, Sze A. Placenta Previa. In: StatPearls [Internet]. Treasure
Island (FL): StatPearls Publishing; 2026. Available from:
