The placenta is an important organ that develops during pregnancy and protects and nourishes your baby. Containing a complex system of blood vessels, the placenta is vital for your baby’s growth and development but is also susceptible to complications related to its location, development, and function.
What is the placenta?
The placenta is a disc-shaped organ that develops in your uterus along with your baby during pregnancy. The placenta is filled with blood vessels, and it is the life-sustaining connection between your blood supply and your baby, which are connected via the placenta and umbilical cord.
By about week 12 of pregnancy, the placenta begins providing nutrients for the growing embryo and also continues to grow.
Just after fertilization, as cells begin to split and differentiate, some of those cells burrow into the lining of your uterus and start forming the placenta. By about week 12 of pregnancy, the placenta begins providing nutrients for the growing embryo and also continues to grow; by the time you reach 40 weeks of pregnancy, the average placenta weighs about a pound.
The placenta has a number of extremely important jobs for you and your baby. It:
- Provides oxygen for baby
- Provides nutrients for baby
- Removes baby’s waste products
- Acts as a barrier to keep mom’s germs away (the placenta keeps baby safe from a lot of bacteria and viruses)
- Acts as a barrier to keep baby’s blood and cells separate (so your body doesn’t reject your baby as a foreign invader)
- Produces hormones
The placenta usually attaches to the top, side, front, or back of the uterus and connects to your baby via the umbilical cord. Placental position is typically evaluated during a second-trimester ultrasound around 20 weeks. Sometimes, the placenta may attach low, near the bottom of the uterus and the cervix (which can cause complications that will be covered below). If the placenta attaches in the front (called an anterior placenta), it might take longer to feel the baby’s movement and, in some instances, it might be more challenging for your provider to detect the baby’s heartbeat. Your placenta can also migrate and move throughout your pregnancy, so a low-lying placenta in early pregnancy may move and no longer be an issue as the pregnancy progresses. With twins, depending on whether they are fraternal or identical (and if identical, when the split occurs), you might have one or two placentas.
After you’ve delivered your baby, the third stage of labor occurs when the placenta detaches from the uterine wall.
After you’ve delivered your baby, the third stage of labor occurs when the placenta detaches from the uterine wall. If you deliver vaginally, you will deliver the placenta the same way, and your provider might have you give one last push to do so. If you deliver via C-section, your provider will remove the placenta after the baby is delivered.
What factors affect placental health?
Certain factors can increase your risk for placental complications. The Mayo Clinic identifies the following risk factors:
- Maternal age, especially after age 40
- Your water (baby’s amniotic sac) breaking before labor
- High blood pressure
- Pregnancy with multiples
- Blood-clotting disorders
- Previous uterine surgery, including a C-section
- Substance use
- Abdominal trauma
What are the most common placental complications?
Placenta previa
As noted before, most placental positions are not problematic. Placenta previa occurs when the placenta attaches low in the uterus. This often places the placenta close to the cervix, sometimes even covering it completely. According to the March of Dimes, placenta previa occurs in approximately 1 in 200 pregnancies. Early in pregnancy, placenta previa is not usually an issue and often fixes itself. Later in pregnancy, there is a high risk of severe bleeding with placenta previa, so delivery via C-section is often recommended. If you had placenta previa in a previous pregnancy, you have a 2-3 percent chance of developing it again.
Placenta accreta
Placenta accreta occurs when the placenta attaches too deeply to the uterine tissue and, as a result, the placenta doesn’t fully detach from the uterus after birth. This occurs in approximately 1 in 530 pregnancies, and it can cause severe and life-threatening bleeding. Placenta increta (when the placenta attaches deep into the uterine muscle) and placenta percreta (when the placenta grows through the uterus, sometimes compromising nearby organs) are different forms of placenta accreta. If you develop these placental complications, your provider will likely recommend a C-section delivery, and you may also need a hysterectomy, which is a surgical procedure to remove your uterus, to prevent life-threatening bleeding. Having had a previous C-section or uterine surgery puts you at an increased risk for placenta accreta.
Placental abruption
Your placenta is supposed to detach from the uterine wall after birth, but when this happens before birth, it is called placental abruption. About 1 percent of women experience placental abruption, and mild cases may not cause problems. If you have moderate or severe placental abruption, your baby may need to be delivered right away. Approximately 10 percent of premature births are related to placental abruption.
Placental insufficiency
A rare but serious placental condition is placental insufficiency, which is when the placenta doesn’t form or function correctly, or if it is damaged. While there are some increased risks for the mom (of preeclampsia and placental abruption in particular), there is significant risk for the baby. If the baby is not getting enough nutrients or oxygen through blood flow, major problems with baby’s growth and development can occur.
Retained placenta
When the placenta fails to be delivered after the birth of a baby, this is called retained placenta. Retained placenta can happen for a number of reasons: contractions are not strong enough, the cervix closes before the placenta is expelled, or placental complications, like placenta accreta, occur. If a retained placenta is not recognized or treated, there are risks of severe bleeding and infection.
What signs and symptoms of placental complications should you watch out for?
For nearly all placental complications, bleeding is a common sign. With some conditions, the bleeding might be accompanied by pain, but frequently the bleeding is painless. While spotting or bleeding during pregnancy can be caused by a number of reasons, any bleeding experienced during pregnancy should be discussed with your provider. Heavy bleeding warrants an immediate call to your provider and a trip to the hospital.
For nearly all placental complications, bleeding is a common sign.
Speaking of bleeding, placental conditions put you at higher risk for postpartum hemorrhage (PPH). PPH usually occurs within one day of giving birth but can occur up to 12 weeks after. PPH can cause your blood pressure to plummet and can result in shock or death if not treated. Signs of PPH include heavy vaginal bleeding that doesn’t slow or stop, signs of low blood pressure and shock (like chills, clammy or pale skin, and rapid heartbeat), nausea, blurred vision, and swelling around the vagina and perineum. If you think you are experiencing PPH, call your provider or 911 immediately.
After delivery
The placenta is a pretty miraculous organ that has the unique job of connecting you and your baby in the womb. Your medical providers will examine your placenta and the umbilical cord after you give birth. If you’re planning to have the hospital dispose of your placenta but you’d still like to see what it looks like, don’t hesitate to ask. As with most things related to birth, the placenta will be messy, but you will be able to see some of the amazing network of blood vessels that supported your baby throughout your pregnancy, as well as how the umbilical cord attaches. The side facing your baby has a smooth membrane covering it, and the side that was attached to your uterus will often look (understandably) bloody and raw.
Many cultures and individuals have different traditions surrounding what happens to the placenta after birth, like consuming it, planting it with a tree, or making a print or other artwork with it. If you’re planning to bring your placenta home with you, check with your hospital or birthing center well in advance, as there are often specific protocols. For some ideas about what to do with your placenta, you can read more here.
References & linked pages:
https://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/in-depth/placenta/art-20044425
https://www.marchofdimes.org/complications/placenta-previa.aspx
https://www.marchofdimes.org/complications/placental-accreta-increta-and-percreta.aspx
https://www.marchofdimes.org/complications/placental-abruption.aspx
https://www.whattoexpect.com/pregnancy/placenta
https://americanpregnancy.org/labor-and-birth/retained-placenta-25592
https://www.medicalnewstoday.com/articles/324554#summary
https://www.healthline.com/health/placental-insufficiency#placenta-functions
https://www.marchofdimes.org/pregnancy/postpartum-hemorrhage.aspx