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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 rest.
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 weeks later
- bleeding after intercourse
- bleeding during the second half of pregnancy
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 (D&C)
- 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
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:
- Transvaginal ultrasound: 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.
- Transabdominal ultrasound: 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 resonance imaging): This imaging scan will help clearly determine the placenta’s location.
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 delivery.
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.
Doctors will decide how to treat your placenta previa based on:
- the amount of bleeding
- the month of your pregnancy
- the baby’s health
- the 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 bleeding
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.
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.
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.
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 delivery: Depending 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 baby.
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:
- putting together a photo album
- writing letters
- reading about your upcoming lifestyle change
Pamper yourself: Indulge in small pleasures, such as:
- buying a new pair of comfortable pajamas
- reading a good book
- watching your favorite TV program
- keeping a gratitude journal
Be sure to rely on your circle of friends and family for conversation and support.