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.
Symptoms associated wih 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 weeks later
bleeding after intercourse
bleeding during the second half of pregnancy
Risk factors for developping 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 (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
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.
Types of plancenta previa
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.