What is placenta previa?
Placenta previa, or low-lying placenta, occurs when the placenta covers part
or all of the cervix during the last months of pregnancy. This condition can
cause severe bleeding before or during labor.
The placenta develops in a woman’s uterus during pregnancy. This sac-like organ
provides the developing baby with food and oxygen. It also removes waste
products from the baby’s blood. The placenta is also referred to as “afterbirth”
because it exits the body after the baby is born.
During pregnancy, the placenta moves as the uterus stretches and grows. It’s
normal for the placenta to be low in the uterus in early pregnancy. As the
pregnancy continues and the uterus stretches, the placenta typically moves to
the top of the uterus. By the third trimester, the placenta should be near the
top of the womb. This position allows the cervix, or the entrance to the womb
at the bottom of the uterus, a clear path for delivery.
If the placenta attaches instead to the lower part of the uterus, it can
cover part or all of the cervix. When the placenta covers part or all of the
cervix during the last months of pregnancy, the condition is known as placenta
previa, or low-lying placenta. Most women with this condition will require bed
Symptoms associated with placenta previa
The main symptom is sudden light to heavy bleeding from the vagina, but if
any of the symptoms below occur, you should seek immediate medical attention:
- cramps or sharp pains
- bleeding that starts, stops, and begins again days or
- bleeding after intercourse
- bleeding during the second half of pregnancy
Risk factors for developing placenta previa
Risk factors for the development of placenta previa include:
- unusual position of the baby: breech (buttocks first)
or transverse (lying horizontally across the womb)
- previous surgeries that involve the uterus: cesarean
delivery, surgery to remove uterine fibroids, dilation and curettage
- being pregnant with twins or other multiples
- prior miscarriage
- large placenta
- abnormally shaped uterus
- having already given birth to one child
- prior diagnosis of placenta previa
- being older than 35
- being Asian
- being a smoker
How is placenta previa diagnosed?
Usually, the first signs of placenta previa will show up during the routine
20-week ultrasound scan. These initial signs are not necessarily a cause for
worry, since the placenta is often lower in the uterus during the early part of
a woman’s pregnancy.
The placenta usually corrects itself. According to the Royal College of
Obstetricians and Gynaecologists, only 10
percent of cases will go on to develop into full placenta previa.
If you experience any bleeding in the second half of your pregnancy, doctors
will monitor the position of the placenta using one of these preferred methods:
Your doctor places a probe inside the vagina to provide an inside view of
your vaginal canal and cervix. This is the preferred and most accurate
method for determining placenta previa.
A healthcare technician places gel on your abdomen and moves a handheld
unit called a transducer around your abdomen to view the pelvic organs.
The sound waves make a picture on a TV-like screen.
- MRI (magnetic
This imaging scan will help clearly determine the placenta’s location.
Types of placenta previa
There are four types of placenta previa, ranging from minor to major. Each
will have its own effect on whether a mother can have a normal delivery or
whether she will need a cesarean delivery. Treatment for placenta previa will
also be based on which type you have.
The placenta only partially covers the opening of the cervix. Vaginal birth
is still possible.
This type begins in early to mid pregnancy. The placenta is positioned at
the edge of the cervix, and there is a good chance of having a vaginal
The placenta begins to grow at the bottom of the uterus. The placenta will
normally push against the cervix but not cover it. Since the border of the
placenta is touching the internal opening of the cervix, any overlap during
labor could cause minor bleeding. However, vaginal births are normally safe.
Major or complete
This is the most serious type. In major placenta previa, the placenta will
eventually cover the entire cervix. C-sections are usually recommended, and in
severe cases, the baby may have to be delivered prematurely.
With all types, heavy or uncontrollable bleeding may necessitate an
emergency cesarean delivery to protect you and your baby.
Treatment of placenta previa
Doctors will decide how to treat your placenta previa based on:
amount of bleeding
month of your pregnancy
position of the placenta and the baby
The amount of bleeding is a doctor’s main consideration when deciding how to
treat the condition.
Minimal to no
For cases of placenta previa with minimal or no bleeding, your doctor will
likely suggest bed rest. This means resting in bed as much as possible, and only
standing and sitting when absolutely necessary. You’ll also be asked to avoid
sex and likely exercise as well. If bleeding occurs during this time, you
should seek medical care as soon as possible.
Cases of heavy bleeding may require hospital bed rest. Depending on the
amount of blood lost, you may need blood transfusions. You may also need to
take medicine to prevent premature labor.
In the case of heavy bleeding, your doctor will advise a C-section be
scheduled as soon as it is safe to deliver — preferably after 36 weeks. If the
C-section needs to be scheduled sooner, your baby may be given corticosteroid
injections to speed up his or her lung growth.
In the case of uncontrolled bleeding, an emergency cesarean delivery will
have to be performed.
Complications of placenta previa
During labor, the cervix will open to allow the baby to move into the
vaginal canal for birth. If the placenta is in front of the cervix, it will
begin to separate as the cervix opens, causing internal bleeding. This can
necessitate an emergency C-section, even if the baby is premature, as the
mother could bleed to death if no action is taken. Vaginal birth also poses too
many risks for the mother, who could experience severe hemorrhaging during
labor, delivery, or after the first few hours of delivery.
Coping and support for expectant mothers
A placenta previa diagnosis can be alarming for expectant mothers. The Mayo
Clinic provides some ideas for how to cope with your condition and how to
prepare yourself for delivery.
Get educated: The more you know, the more
you will know what to expect. Get in contact with other women who have been
through placenta previa births.
Be prepared for your cesarean
on the type of your placenta previa, you might not be able to have a vaginal
birth. It’s good to remember the ultimate goal — the health of you and your
Enjoy bed rest: If you are active, bed rest
can feel confining. However, you can use the time wisely by catching up on
small projects, such as:
together a photo album
about your upcoming lifestyle change
Pamper yourself: Indulge in small pleasures,
a new pair of comfortable pajamas
a good book
your favorite TV program
a gratitude journal
Be sure to rely on your
circle of friends and family for conversation and support.