Bleeding during pregnancy is a frightening experience that can elicit worry and panic in an expectant mother. Fortunately, not all bleeding indicates a major problem or poses an immediate risk to a baby’s health.
Light, painless bleeding during the 2nd and 3rd trimesters of pregnancy may be the result of a condition known as placenta previa, which affects about 1 in 200 pregnancies in the U.S. each year.
If you experience bleeding, with or without pain, at any time during your pregnancy, it’s important to contact an experienced OB-GYN immediately.
To understand placenta previa, it’s necessary to know how the placenta functions in a healthy pregnancy.
The placenta is a temporary organ that develops on the wall of a woman’s uterus during pregnancy. It provides the growing baby with essential oxygen and nutrients while in the womb. These nutrients are delivered to the baby through the umbilical cord, which connects the baby and the placenta.
Normally, the placenta attaches to the top or side of the uterine wall. In placenta previa, however, the placenta attaches to the cervix, which is located at the base of the mother’s uterus.
Placenta previa can be divided into 3 categories. Which type you have depends on how much of your cervix is covered by your placenta.
The more your placenta covers your cervix, the more likely you are to experience symptoms and complications from placenta previa.
The most common symptom of placenta previa is bright red vaginal bleeding during the 2nd and 3rd trimesters of pregnancy that is not accompanied by pain. Some women also experience mild contractions.
The cause of placenta previa is still unknown, but women are more likely to experience placenta previa during their pregnancy if they:
In order to diagnose placenta previa, your doctor will need to ask you questions about your health history, do a physical exam and perform an ultrasound. The ultrasound will show where your placenta is located and how much of your cervix is covered by your placenta. If placenta previa is seen on ultrasound, your doctor will likely order additional ultrasounds to monitor the location of your placenta as your pregnancy progresses.
If your initial ultrasound shows that you have placenta previa, there’s no reason to panic. Most of the time, placenta previa resolves on its own before the baby is born. In fact, in one study of more than 1,400 women, 98.4 percent of placenta previa cases diagnosed during the 2nd trimester resolved before the end of pregnancy.
Because a woman’s uterus enlarges throughout pregnancy to accommodate her ever-growing baby, her placenta often pulls away from her cervix as her uterus expands. Women diagnosed with partial or marginal placenta previa have a greater chance of their placenta moving completely off of their cervix before delivery than those diagnosed with complete placenta previa.
The biggest risk with placenta previa is severe bleeding, also known as hemorrhage. This is most likely to occur toward the end of pregnancy as the uterus begins thinning out in preparation for childbirth. The more the cervix is covered by the placenta, the greater the risk of bleeding.
Other potential complications of placenta previa include:
There is no cure for placenta previa, but your doctor will monitor your symptoms to make sure you and your baby remain healthy and safe. If your doctor has any concerns, they may recommend:
Because complete placenta previa blocks the opening for a baby to be born vaginally, women whose placenta previa doesn’t resolve before the end of their pregnancy will need to have a C-section to deliver their baby safely.
If you experience bleeding at any time during your pregnancy, it’s vital that you contact a qualified OB-GYN right away so they can assess you and your baby and determine a cause. Although a small amount of painless bleeding often isn’t a cause for concern, your doctor will monitor your symptoms and recommend appropriate treatment based on your individual situation.