During pregnancy, your body nourishes and supports your growing baby as well as your baby’s lifeline – the placenta. The placenta is a complex, lifegiving organ that grows inside the uterus alongside your baby and connects to your baby via the umbilical cord. The placenta’s sole purpose is to provide nutrients and oxygen to your baby throughout the pregnancy, while also removing waste from your baby’s blood.
A well-functioning placenta is essential for a healthy pregnancy. The growth and health of your baby depends on the quality and effectiveness of your placenta. Various factors can affect placental health, including advanced maternal age (over 40); high blood pressure; blood-clotting disorders; abdominal trauma; prior uterine surgeries; etc. Thankfully, your provider will assess your placenta via ultrasounds, as needed throughout your pregnancy, to monitor its growth, location as well as any potential complications.
We asked our SLUCare maternal-fetal medicine specialists, who are based at SSM Health St. Mary’s Hospital – St. Louis and the SSM Perinatal Center, for their input on how placenta placement can affect a woman’s pregnancy, labor, and/or delivery. They also addressed three placental complications – placenta previa, accreta and abruption – and what patients should know.
Placenta Placement
Generally, the placenta attaches at the top of the uterus; however, in some cases, it may attach along the front wall, back wall, or side walls. If that’s the case, your doctor will monitor you with regular prenatal checkups to be sure you don’t have any complications. In very rare cases – one of out of every 200 pregnancies – the placenta will cover the bottom of the uterus (placenta previa), which requires special monitoring and other considerations.
The following is an overview about the various placenta placements and how these can impact your pregnancy and/or delivery:
Anterior (front wall) placement doesn’t negatively impact the pregnancy or birth; however, it may make it harder to feel your baby as the baby is cushioned by your placenta at the front of your stomach. The baby is also more likely to be back-to-back (posterior) meaning baby’s spine is against your spine, which can increase your back pain. Babies usually rotate to a vertex (head down) position during labor and delivery.
Posterior (back wall) placement is when the placenta has implanted into the back of your uterus. In this case, you may feel your baby’s movements earlier and stronger as well as allowing your baby to get into the most optimum position for birth (spine at the top of your belly).
Placenta previa occurs when the placenta implants over the cervix, obstructing the birth canal. This is a high-risk condition that’s often diagnosed on routine ultrasound or when vaginal bleeding occurs. Possible causes of placenta previa include multiparity (twins/triplets); advanced maternal age (35+); previous placenta previa; previous C-section; and/or smoking during pregnancy.
When the placenta is completely covering the cervix, it’s too dangerous to deliver the baby vaginally, so a C-section section is required. An extra ultrasound scan is usually performed at 32-weeks gestation to determine the severity of your placenta previa and how it will be managed in the third trimester. You may be on pelvic rest for the remainder of the pregnancy if the placenta previa does not resolve. If any bleeding occurs, you need to contact your provider immediately. Significant bleeding may require premature delivery.
Other Placental Complications
In addition to placenta previa, other potential – yet extremely rare – complications include placenta accreta and placental abruption.
Placenta accreta is a serious, high-risk pregnancy condition that occurs when the placenta grows too deeply into the uterine wall. With most pregnancies, the placenta detaches from the uterine wall after childbirth. However, with placenta accreta, part or all of the placenta remains attached, which can cause severe blood loss after delivery. Affecting 0.2 percent of pregnancies, placenta accreta is commonly associated with abnormalities in the lining of the uterus, typically due to scarring after a C-section or other uterine surgery. The risk of placenta accreta increases with:
- The number of C-sections or other uterine surgeries
- Placenta previa
- Maternal age (older than 35 years)
- The number of pregnancies
If you’re diagnosed with placenta accreta during your pregnancy, you'll likely require advanced monitoring and an early C-section delivery. If the condition worsens, you may also require a hysterectomy following your baby’s birth.
Placental abruption occurs when the placenta peels away from the inner wall of the uterus before delivery — either partially or completely – which can deprive your baby of oxygen and nutrients and cause you to bleed heavily. Placental abruption could result in an emergency situation requiring early delivery.
When to Call Your Doctor
Problems with the placenta can occur suddenly and are often severe and, in some cases, life-threatening. With regular prenatal checkups, your provider will monitor your pregnancy and placenta to help you avoid experiencing any of the complications outlined above. More importantly, if you experience any of the following symptoms, be sure to contact your provider immediately:
- Vaginal bleeding
- Fast or constant contractions
- Severe back or abdominal pain, a hard tummy that doesn’t relax
- Decreased fetal movement
For more information about placenta placement and associated complications, talk to your provider or maternal-fetal medicine specialist. You can also learn more about the services available at SSM Health for high-risk pregnancies by visiting: https://www.ssmhealth.com/maternity/high-risk-pregnancy
If you are in the St. Louis region, SLUCare maternal-fetal medicine physicians are leaders in providing specialized care for every aspect of high-risk pregnancy, including placenta previa and placenta accreta. As every expectant mother is different, these specialists tailor your care to fit your needs. They can be a consultation resource for you and your primary obstetrician; take over as your primary obstetrician for the remainder of your pregnancy and delivery; or provide any combination of services as needed. SLUCare’s maternal-fetal medicine specialists offer services at the SSM Perinatal Center and SSM Health St. Mary's Hospital – St. Louis. To request an appointment with one of these specialists, call (314) 977-7455.
