COVID-19 During Pregnancy Tied To Higher Risk Of Pre-Eclamps
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Pregnant women with COVID-19 disease are at a higher risk of developing pre-eclampsia, shows a recent review by Brazilian researchers. Pre-eclampsia is a pregnancy complication characterized by persistent high blood pressure, usually in the second half of pregnancy or shortly after delivery, and causes serious harm to the mother and baby.

The authors analyzed a large set of published data and concluded that the presence of SARS-CoV-2 in the maternal organism can cause alterations in levels of angiotensin-converting enzyme 2 (ACE2), the protein to which the virus binds in order to invade cells, and thereby impair the functioning of systems that depend on ACE2 to regulate blood pressure. Besides serving as a receptor for the virus, ACE2 plays a key role in establishing blood flow in the placenta and in the cardiovascular adaptations that occur during pregnancy.

"ACE2 plays a very important adaptive role in the maternal and fetal circulatory system, and in placentation. However, because it's also a receptor for SARS-CoV-2, it increases risk to the placenta in pregnant patients with COVID-19, because the organ becomes a target for the virus, alongside the lungs, kidneys and heart. Our review showed that the response varies greatly from one patient to another, and manifestations take different forms," Mariane Bertagnolli, principal investigator for the study, told.

~ Vertical transmission

In a study by researchers in Taiwan, published in February 2021, 8.8% of 105 newborns tested positive for SARS-CoV-2. 25% of babies born to mothers who had confirmed COVID-19 manifested fever, accelerated breathing, shortness of breath, and vomiting. The researchers were unable to ascertain whether the symptoms resulted from premature delivery due to maternal COVID-19 or were directly caused by the disease.

Other research groups have found viral particles in different parts of the placenta, which in mothers with the disease shows signs of inflammation and lesions consistent with vascular malperfusion. Immune cells probably infected by the virus have also been found in the placenta.

Apart from the fact that ACE2, the receptor for SARS-CoV-2, is abundant in the placenta, the researchers found that the incidence of severe COVID-19 among pregnant women could be due to inhibition of the enzyme's action by the viral infection. Because the virus uses it to invade cells, infection probably reduces the availability of ACE2 and its capacity to protect the organism during pregnancy.

"A deficit of ACE2 can cause an imbalance in the renin-angiotensin system and an increase in the peptide angiotensin 2, a vasoconstrictor, driving up the mother's blood pressure and leading to pre-eclampsia," said a co-author of the study.