New research published this week gives a greater understanding of why the CDC warned of an increased risk of stillbirth for women infected by SARS-CoV-2 during pregnancy in November.
In November, the Centers for Disease Control and Prevention warned of an increased risk of stillbirth for women infected by SARS-CoV-2 during pregnancy. New research published this week gives a greater understanding of why that is, uncovering options for potential intervention.
The study, led by Dr. David Schwartz and published in the journal Archives of Pathology & Laboratory Medicine, looked at 64 stillborn babies and 4 that died within a week of delivery. The 68 mothers were from 12 countries. All were unvaccinated and had been infected with COVID-19 while pregnant. Every placenta studied had tested positive for COVID-19 infection.
What researchers found was startling. The virus wasn’t killing the unborn directly. It was severely damaging the placenta.
Unlike viruses such as Zika that can cause damage or congenital disabilities to the fetus in utero, the novel coronavirus can attack and destroy the placenta. The placenta is the only disposable organ in the body, grown for each pregnancy and discarded by the body after delivery. It is the fetus’ lifeline and essential for a healthy pregnancy and delivery.
“We have never seen this level of destruction from an infectious illness before. It rendered the placenta unfit to carry out its duties,” said Schwartz. “These fetuses and newborns died from asphyxiation due to lack of oxygen.”
The researchers are calling the phenomena SARS-CoV-2 placentitis. Of the 68 studied, 63 of the placentas had massive perivillous fibrin deposition, which, in early pregnancy, leads to miscarriage in nearly 1 in 3 affected. This build-up causes clotting to the placenta’s vascular system.
The placentas had over two-thirds of the tissue involved with some infections leading to more than 90% of the placenta being dead. While fibrin deposition can also occur in normal pregnancies, not at this level. A fetus cannot survive the level of fibrin deposit the researchers found.
SARS-CoV-2 placentitis also caused death in the protective cell layer and unusual inflammation was found in the organ.
Thirty autopsies were performed and found no fetal abnormalities, except for the signs of suffocation to the fetus. The placentas studied were clearly too damaged to deliver oxygen and nutrients to the baby. The coronavirus was detected in the organs of some of the babies autopsied but did not appear to be the cause of death.
Pregnancy weakens the immune system to prevent the body from attacking the growing life inside, leaving pregnant women more vulnerable to all types of infection. COVID-19 infection can cause placenta damage in women who do not experience severe disease. SARS-CoV-2 placentitis could be their only symptom.
Statistically, the numbers are, thankfully, still low. Before the pandemic, 0.59% of pregnancies resulted in stillbirths. That number increased during the virus’s early days but really took a jump when the Delta variant came on the scene. The CDC found the stillbirth rate at 2.7% in COVID-19-positive pregnancies. Studies have not yet been done to determine the rate with the omicron variant.
Full vaccination remains the best line of defense against COVID-19 infection. It is now strongly recommended for pregnant women by the CDC, the American College of Obstetricians & Gynecologists, and the Society for Maternal-Fetal Medicine.
Obstetricians are also being advised to perform third-trimester ultrasounds on women who have had a COVID-19 infection during pregnancy. The additional screenings could reveal trouble in the placenta. While medicine cannot reverse damage to the placenta, early delivery may have more hopeful outcomes than leaving the baby at risk of asphyxiation in utero.
