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A small, European study, involving 38 pregnant women infected with SARS-CoV2 (the virus that causes COVID-19) and published recently in the journal The Lancet Regional Health, suggests that infection with the virus may cause abnormalities in the fetus and in the placenta. Conducted by researchers at the Medical University of Vienna, in Austria, the research made use of magnetic resonance imaging (MRI). Using MRI imaging obtained from July 2020 to July 2022, the scientists examined fetal development and the placenta, both in the 38 women who tested positive for SARS-CoV-2 and in a control group of 38 uninfected women who were also pregnant. In both the control group and the infected group, the MRI was conducted an average of 83 days after a positive test for presence of the virus.
Among the 38 infected cases, 18 were Omicron variant infections, while the rest were infections with pre-Omicron variants of SARS-CoV2, such as the wild-type (ancestral variant), Alpha, or Delta. At the time of MRI evaluation, pregnancies ranged from 19 to 36 weeks gestation, with a mean of 28 weeks.
Of the women infected with pre-Omicron variants, 30 percent demonstrated placentae that were thickened and globular. These same effects were observed in 27.8% of the Omicron group, whereas women of the control group (uninfected) did not show these abnormalities in their placentae. Doctors know that this type of placental abnormality entails an elevated risk for pregnancy complications, such as intrauterine growth restriction (IUGR) and preeclampsia. These complications did show up in some of the infected women, leading to a small number of cases of further complications that included spontaneous abortion and a need for cesarean birth a few weeks prior to term. However, most of the babies were born at term.
As you may remember from some previous posts here on The Pulse, preeclampsia is characterized by elevated blood pressure (systolic >140 mm Hg and/or diastolic >90 mm Hg, detected on two separate readings at least 4 hours apart) occurring after 20 weeks gestation. Along with the elevated blood pressure, there is dysfunction of a maternal organ –usually the kidney, showing up as protein in the urine. Preeclampsia affects about 5 percent of expecting mothers and is an obstetric emergency that threatens the mother and especially the fetus. In extreme cases, it can be a prelude to other, worse conditions. One is called HELLP syndrome, and the other is eclampsia. Both can lead quickly to maternal death. For a patient who is diagnosed with preeclampsia, if the preeclampsia is severe, the first goal is to prevent seizures –a development that would indicate transformation from preeclampsia into eclampsia. The brain typically is checked with an MRI scan and electroencephalography (EEG). The patient is given magnesium sulfate to prevent seizures if doctors determine that the risk is high. In such cases, if the pregnancy is beyond 34 weeks, doctors will deliver the baby early. If it’s before 34 weeks, doctors will administer steroids to accelerate maturation of the fetal lungs to carry out delivery as soon as possible.
Also called fetal growth restriction, IUGR is characterized by a fetus that is small, even accounting for the family. Presence of IUGR means that not enough nutrients and/or oxygen are getting to the fetus by way of the placenta and the blood vessels of the umbilical cord. Causes of fetal growth restriction themselves fall into two categories: placenta-mediated growth restriction and non-placenta-mediated growth restriction. Given the placental abnormalities seen in infected women in this new study, any related IUGR would fall into the first category, meaning placenta-mediated. Signs of fetal growth restriction, other than the fetus being small for gestational age include abnormal Doppler studies revealing abnormal circulation in the placenta, reduced volume of amniotic fluid, reduced movement of the fetus, and abnormal continuous fetal heart monitor readings.
As for the issue of vaccination status, 11 percent of the Omicron-infected women who were unvaccinated against SARS-CoV2 showed the placental abnormalities, while 17 percent of women with three vaccine doses showed the abnormalities. This means that the study failed to demonstrate that vaccination can prevent placental complications of SARS-CoV2 infection. Along with the fact that the number of participants in the study was small, it is important to keep in mind that the evidence is extremely strong that three doses of a vaccine protects pregnant women from developing severe COVID-19, the kind of COVID-19 that leads to hospital admission and admission to an ICU, which in turn is associated with poor outcomes for the baby.