Pregnancy can involve several medical terms that may seem concerning at first. One of these is low-lying placenta, also referred to as placenta praevia. Below is an explanation for informational purposes.
What Is the Placenta?
During gestation, a specialized organ known as the placenta develops within the uterine environment. Its primary role involves facilitating the exchange of vital oxygen and nourishment to the growing fetus while simultaneously removing metabolic byproducts from the fetal circulatory system. While it commonly affixes itself to the upper or lateral aspects of the uterus, instances can occur where placental attachment takes place in the lower uterine segment. This specific condition is medically termed a low-lying placenta or placenta previa.
What are Low-Lying Placenta and Placenta Praevia?
The placenta develops early in pregnancy at the location where the fertilized egg implants into the uterine lining. It may attach to various parts of the uterus, including the front, back, top, or sides.
In most pregnancies, the placenta is located in the upper portion of the uterus. Occasionally, it is positioned lower and may be close to or covering the cervix (the opening to the birth canal). The following are the main types:
- Low-lying placenta: The edge of the placenta is less than 2 centimeters from the cervix but does not cover it.
- Placenta praevia: Placenta previa is a condition characterized by the placenta partially or entirely obstructing the cervical opening.
These conditions are generally identified during a routine ultrasound scan conducted between 18 and 21 weeks of pregnancy.
Are Low-Lying Placenta or Placenta Praevia Common?
Yes. A low-lying placenta is relatively common during the mid-second trimester. Approximately 1 in 10 women are diagnosed with this at the 20-week ultrasound scan. However, this is often temporary, as the placenta typically shifts upward as the uterus expands.
By the third trimester, about 90% of low-lying placenta cases resolve naturally. If the placenta remains low or continues to cover the cervix later in the pregnancy, it is classified as placenta praevia. This is less common, seen in about 1 in 200 pregnancies at full term.
What are the Symptoms of a Low-Lying Placenta or Placenta Praevia?
Many individuals with a low-lying placenta experience no symptoms. However, placenta praevia can be associated with the following signs, particularly in the second or third trimester:
- Painless, bright red vaginal bleeding (which may occur more than once or suddenly)
- Bleeding following sexual intercourse
- Usually no pain or cramping, though mild discomfort may occur in some cases
- Possible signs of preterm labor, such as uterine contractions or pelvic pressure
Who is at Risk of Developing Placenta Praevia?
Placenta praevia can occur in any pregnancy, but certain risk factors may increase its likelihood:
- Previous cesarean section
- History of uterine surgery (e.g., fibroid removal or dilation and curettage)
- Multiple pregnancy (twins or more)
- Maternal age above 35 years
- Smoking during pregnancy
- Pregnancy conceived through in vitro fertilization (IVF)
- Past history of placenta praevia
Having risk factors does not guarantee the development of the condition but may require closer monitoring.
How Can a Low-Lying Placenta or Placenta Praevia Affect mother and Baby?
In most cases, a low-lying placenta early in pregnancy does not have long-term effects, as it usually moves upward. If it remains low or covers the cervix later in pregnancy, the following complications may occur:
- Vaginal bleeding in the second or third trimester, possibly heavy and sudden
- Risk of preterm labor or early delivery
- Likelihood of cesarean section if the placenta still covers the cervix at the time of labor
- Possible hospital admission for monitoring in cases of severe bleeding
- Restrictions on physical activities, such as avoiding sexual intercourse or vaginal examinations, to prevent bleeding
Healthcare providers will monitor the condition with follow-up scans and give specific medical advice to ensure the pregnancy progresses safely.
Conclusion
A diagnosis of low-lying placenta or placenta praevia may cause concern, but in most cases, the condition resolves on its own as the pregnancy progresses. With regular monitoring and proper medical care, most individuals go on to have healthy pregnancies and deliveries.
If placenta praevia persists into the later stages of pregnancy, the medical team will develop an appropriate management plan to ensure the safety of both the pregnant individual and the baby.
