The Effects of COVID-19 on the Placenta

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How SARS-CoV-2 (the virus that causes COVID-19) affects pregnant women is a growing field of research. Recently, scientists have studied the effects of infection with COVID-19 on the placentas of pregnant women. Before we go into their findings, let’s review what the placenta is and how it functions during pregnancy.

What is the placenta?

The placenta is a temporary organ, basically a sac of blood vessels, that attaches to the inner wall of the uterus and connects to the fetus via the umbilical cord. It is one of the first things to develop in pregnancy. It functions as the fetus’ lungs, liver, and kidneys to provide oxygen and nutrients while removing waste products. The placenta also influences some of the hormonal changes that take place in a pregnant woman’s body. Damage to the placenta could affect the health of both mother and fetus.

I thought COVID-19 was a lung disease, how could it possibly affect the placenta?

SARS-CoV-2 is not like the other coronaviruses scientists have had experience with. Whereas the coronavirus that causes the common cold mostly attacks the upper respiratory system, and SARS and MERS attacked primarily the lungs, scientists are finding out that SARS-CoV-2 is first attacking the lungs, and from there, gaining entry to the blood vessels.

As we all know, blood vessels are everywhere in our bodies providing oxygen and nutrients to our muscles and organs while transporting carbon dioxide back to the lungs and waste products to other organs where they can be expelled. If SARS-CoV-2 gains entry to the blood vessels, it is conceivable that it could have a detrimental effect on every one of our organs. We have already seen how COVID-19 affects the heart and the kidneys. It makes sense, then, that the virus would have an effect on the placenta, an organ whose main function is to provide oxygen and nutrients to the fetus and is primarily made of blood vessels.

Once in the blood vessels, the virus attacks the interior lining called the endothelium, which is a smooth layer of cells that allows the blood to flow efficiently through the vessels. When the endothelium is disrupted, clots can form, or previously stable plaques could break off and impede blood flow at the site or elsewhere.

Because of the concern for the health of both mother and fetus, extra monitoring for pregnant women diagnosed with COVID-19 should be considered.

How does COVID-19 affect the placenta?

Given how SARS-CoV-2 can invade the blood vessels, it is clear why scientists have seen that infection with COVID-19 could impede the flow of blood between mother and fetus. In a small cohort of pregnant patients who tested positive for COVID-19, placental injury included blood clots and abnormal blood vessels that affected how much blood was getting to the fetus. Additionally, some of the placentas were found to be smaller than expected.

There is concern that the placental injury caused by COVID-19 infection could lead to preeclampsia and hypertension in the mother and possibly miscarriage, intrauterine growth restriction, or preterm birth for the fetus, although this was not the case in the small group of patients that have been studied.

Because of the concern for the health of both mother and fetus, extra monitoring for pregnant women diagnosed with COVID-19 should be considered. A non-stress test, a noninvasive test in which the baby’s heart rate in response to its own movements is measured, is one way to monitor whether or not a baby in utero is getting a sufficient oxygen supply. Frequent ultrasounds may also be considered to monitor the fetus’ growth.

Should I be concerned?

According to the information we have, although infection with COVID-19 during pregnancy could lead to placental injury, the babies born to these women have been healthy. This could be because the placenta has a built-in safety mechanism in that normally we see a “redundancy” of blood vessels. That is to say, there are more vessels in the placenta than are required to support a healthy pregnancy. However, if a woman has a condition that can affect the robustness of the placenta, or if the placenta is somehow damaged or develops in the wrong location, additional injury by SARS-CoV-2 could compromise her or her baby’s health. If you are concerned or think you may have contracted the virus during your pregnancy, do not hesitate to ask your physician about this.

As always, it is better to avoid being infected with COVID-19 in the first place. Make sure you are physically distancing by staying at least 6 feet away from others (with whom you are not isolating) at all times. Wear a mask, and ask others to wear a mask around you. Wash your hands with soap and water thoroughly and often.

Janette DeFelice
Dr. Janette DeFelice is a writer currently focusing on how the changing environment affects our health. She holds a Doctor of Medicine degree from Chicago Medical School where she taught clinical and diagnostic skills to beginning medical students, and a Master’s degree in Humanities from the University of Chicago. She also has a Bachelor’s degree in Political Science. Her writing can be seen online at BeTheChangeMom, ChicagoNow, and Medium, and she’s very excited to have published her first novel, Delia Rising: A Ballet in Three Acts. She lives in Chicago’s west suburbs with her school-age twins, her husband, and a family cat named Clara Barton.

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