Coronavirus can cause severe placental damage leading to foetal distress

The virus that causes COVID-19, SARS-CoV-2, can damage the placenta and cause the foetus to suffer from oxygen deficiency. These are the main findings from a study led by Mehreen Zaigham, clinical researcher at Skåne University Hospital and Lund University.

“Placental dysfunction is an unusual but serious complication of SARS-CoV-2 infection during pregnancy. We recommend all women who are pregnant, or planning on becoming pregnant to get vaccinated, even if they have had COVID-19 before”, Mehreen Zaigham says.

The study has been published in the British Journal of Obstetrics and Gynaecology. 

“Studies from different countries during the pandemic have shown an increased risk of mortality and morbidity in pregnant women and foetuses. However, we did not see the same trend in Sweden. In connection with the different waves of the pandemic, we in healthcare, started seeing cases where there were signs that the placenta and foetus could have been adversely affected by COVID-19, Mehreen Zaigham says.

In a retrospective case series, Mehreen Zaigham and her research colleagues examined 14 stillborn and live-born infants, including one twin birth) from seven different maternity units in Sweden. In all cases, the pregnant women had tested positive for COVID-19 and were unvaccinated. All placentas were infected with the virus and in half of the cases, the virus had also infected the foetus.

Five stillborn cases were included in the study and nine live-born cases. Of the live-born cases, two newborns passed away shortly after birth due to their injuries.

By analysing samples from the placentas, the researchers concluded that the placentas were severely damaged due to SARS-CoV-2 related inflammation in the placentas. The damages had caused a lack of oxygen to the foetus intrauterine.

“We could see that the placentas were infected with the virus and that it caused tissue destruction in the form of cell death, inflammation and fibrin deposition. As a result, the placentas could not provide oxygen and nutrients to the foetuses. This is characteristic of a COVID-19 infection, there is nothing else that could have affected the placentas in this way”, Mehreen Zaigham says.

The researchers also noted that the placental functions deteriorated in a rapid way.

“In the cases where the infants survived, we saw that it took approximately six days from the mother showing the first COVID symptoms to the point where the infection affected the foetus in the form of signs of oxygen deficiency. In cases where the children were stillborn, it took an average of 11 days before foetal death was discovered.”

Some of the Swedish findings are part of an international study that looked more closely at 68 cases from 12 different countries. In all cases, there was the same type of damage to the placenta as in the Swedish study.

Mehreen Zaigham emphasises that the vast majority of pregnant women infected with COVID-19 will exhibit mild symptoms and not be develop this severe placental complication.

“This is an uncommon but severe complication of COVID-19 infection in pregnant women. Due to its severity, we recommend all women who to get vaccinated, even if they have had COVID before. In our data, there was no case of vaccinated women being affected by this complication. It is therefore of great importance that pregnant women continue to get vaccinated against COVID-19, follow the recommendations and seek healthcare if they feel changes in foetal so we can investigate why”, Mehreen Zaigham concludes.