What to Know About the Placenta During Pregnancy

During pregnancy, your body does many amazing things. Aside from developing your baby over the course of nine months, it also creates a vitally important organ that exists only during pregnancy: the placenta. This organ nourishes your baby throughout your entire gestation, and it also serves to eliminate waste from them. Keep reading to learn more about the placenta, including its role in pregnancy, how to keep it healthy, possible complications, and more.

What Is the Placenta?

The placenta is an organ that exists during pregnancy. It begins developing in the uterus after the fertilized egg implants into your uterine wall. Composed of blood vessels, it connects to your baby via the umbilical cord, and it even contains the same genetic composition as your little one!

During pregnancy, your placenta helps nurture your baby's development by acting as their lungs, stomach, kidneys, and liver. It helps them to eat and breathe.

What Does the Placenta Do?

The placenta has some important roles during pregnancy. It works to provide oxygen, antibodies, and nutrition to your baby in the womb, and it also serves as a waste removal system.

"The placenta converts nutrients from the maternal circulation and turns them into energy for the developing fetus," says Sasha Andrews, M.D., a board-certified maternal-fetal medicine specialist at Pediatrix Medical Group. "These energy sources include glycogen, cholesterol, and protein."

The placenta produces hormones "that increase the supply of glucose, relax the uterus, and help with fetal organ development," says Dr. Andrews. It also "facilitates transfer to gasses such as oxygen from the [parent] to the fetus."

What's more, this important organ even regulates your physiology and metabolism. For instance, your placenta produces hormones and molecules such as human placental lactogen (HPL), relaxin, oxytocin, progesterone, and estrogen. Not only do these hormones benefit your baby, but they also help your body prepare to make milk, boost your metabolism, and more.

Where Is the Placenta Located?

Your placenta, which is a completely separate organ designed to support your pregnancy, is located within your uterus. It consists of parenchyma, or placental tissue, the amniotic membranes, and the umbilical cord, says Dr. Andrews. "It can implant anywhere within your uterine lining, but is usually in the mid to upper portion of the uterus."

Typically, the placenta develops wherever the fertilized egg implants and can grow anywhere in the uterus. If your pregnancy is like most, it will be located in the upper part of your uterus (fundal position). When the placenta is located in the front of the uterus, it's called an anterior placenta, says Lisa Becht, M.D., FACOG, a double board-certified fertility specialist with HRC Fertility. Other possible locations include the right or left side of the uterus (lateral) and the back of the uterus (posterior).

Possible Complications With the Placenta

In most cases, the placenta operates like normal. But sometimes a problem can arise, which can threaten the pregnancy and the pregnant person. Here are some potential issues that can occur with the placenta.

Placenta Previa

When the placenta is low-lying, and it partially or completely covers the cervix, this is known as placenta previa. In addition to increasing the risk of postpartum hemorrhaging, placenta previa usually prevents people from having a vaginal birth, says Dr. Becht.

Placenta previa can also increase your risk for placenta accreta spectrum disorders (PAS), which includes placenta accreta, placenta increta, and placenta percreta, says Lyndsey Harper, M.D., an OB-GYN, associate professor for Texas A&M College of Medicine, and CEO/founder of Rosy. According a study published in the International Journal of Women's Health, PAS "describes a clinical situation where the placenta does not detach spontaneously after delivery and cannot be forcibly removed without causing massive and potentially life-threatening bleeding."

Most of the time, placenta previa is diagnosed partway through the pregnancy with an ultrasound. Sometimes it's spotted after people experience painless vaginal bleeding in the second or third trimester. When uncontrolled bleeding from placenta previa occurs, you may need a blood transfusion or even a hysterectomy.

Placenta Accreta

If the placenta implants too deeply, this can cause placenta accreta, which may lead to complications at delivery, says Dr. Harper. That's because the placenta doesn't separate correctly from the uterine wall after birth. Placenta accreta usually requires you to have a C-section, and it can increase the chance of severe maternal bleeding. Some people with placenta accreta also have a hysterectomy with their C-section.

Placental Abruption

If the placenta completely or partially tears away from the uterine wall before delivery of the fetus, you'll experience placental abruption, says Dr. Harper. This condition can lead to less blood flow to the baby and major hemorrhaging for the pregnant person.

Placental abruption typically takes place after week 20 of pregnancy. Thankfully, the prevalence is low, with only about 0.4% to 1% of people experiencing this complication. People with placental abruption may have abdominal pain, vaginal bleeding, cramping, uterine contractions or tenderness, and decreased fetal movement.

Twin to Twin Transfusion Syndrome

In pregnancies with multiples, there may be one or more placentas. If there's only one, the babies have to share a blood supply and nutrients, says Dr. Harper. This can sometimes lead to complications such as twin to twin transfusion syndrome, where the babies get unequal blood flow from the placenta.

Twin to twin transfusion syndrome typically occurs in about 10% to 15% of identical twins that share the same placenta. For this reason, health care providers will often attempt to determine early on if the twins share the same placenta or each have their own source of oxygen and nutrients. If only one placenta is identified, then a treatment plan can be developed if necessary.

Placental Insufficiency

Placental insufficiency occurs when the placenta is not working optimally, says Dr. Becht. "This insufficiency means the baby may be getting fewer nutrients, oxygen, and blood flow." When this happens, it can lead to intrauterine growth restriction (IUGR) as well as potential long-term complications for your baby. Stillbirth is also a possibility, she says.

"Placental insufficiency also occurs because of abnormal implantation, along with poor development of vascular connections, which can lead to preeclampsia, or high blood pressure in pregnancy," explains Dr. Andrews.

Keeping the Placenta Healthy During Pregnancy

When it comes to keeping your placenta healthy, you should follow the same tips you would for a healthy pregnancy, such as eating a well-balanced diet, exercising regularly, avoiding alcohol, quitting tobacco use, and refraining from drug use, says Dr. Andrews. "You also should confirm with your doctor that any over-the-counter or prescription medications [you are taking] are safe."

Meanwhile, if you have any pre-existing medical conditions or a history of pregnancy complications and you're considering conceiving, it's always a good idea to discuss any concerns with a health care provider. They can let you know what can be done beforehand to optimize your chances of a healthy pregnancy and delivery, says Dr. Andrews.

Delivering the Placenta

After your baby is delivered and the cord is clamped, the placenta is delivered. "This usually occurs within 30 minutes after birth," says Dr. Andrews. "Your obstetrician or midwife may apply gentle traction to the umbilical cord to encourage it to separate from the uterus."

If the placenta does not separate from the uterine wall (called retained placenta), there is a concern for bleeding and infection, adds Dr. Becht. "Uterine massage, manual extraction, and a D&C [dilation and curettage] are options to get it delivered."

If you have a C-section, the placenta is removed, but usually with more assistance from the obstetrician, she adds. "This involves massaging the fundus, or top, of the uterus and applying traction to the cord, so the placenta can deliver through the uterine incision. Afterwards, the inside of the uterus is inspected to ensure there are no retained portions of placenta or amniotic membranes."

What Happens to the Placenta After Birth?

Many times, after the placenta is examined to ensure it is intact, it will be discarded. But some people choose to bank the placenta. Banking is often done with hope that there may be new therapies in the future that it could be used for, says Dr. Becht. "Placental tissue banking is less common than cord blood banking," says Dr. Andrews. "But neither choice is particularly common given the cost associated with these options. Another option to consider is public cord blood donation."

If you're unsure what to do with the placenta after birth, discuss your options with your health care provider. Together, you can decide what's best for you and make a plan to handle this part of your labor and delivery.