A baby born at Skåne University Hospital, Sweden, last year tested positive for COVID-19 and a study of the case has now established that the baby was already infected whilst in the mother’s womb.
The new study provides answers to several important questions on how both mothers and babies can be affected by the infection. The study is now published in the scientific journal British Journal of Obstetrics & Gynecology.
“In our study we were able to exclude that the baby was infected outside the mother’s womb. It can be said that we put together a complex puzzle and that the circumstances in this specific case have given us unique opportunities to analyze and draw conclusions that might otherwise be difficult,” says Mehreen Zaigham, doctor in gynecology at Skåne University Hospital.
Infected via the placenta
The mother came to the hospital with symptoms that were suspected to be COVID-19. The unborn baby showed signs of lack of oxygen and a low heart rate, after which an emergency caesarean section was performed. The baby was separated from the mother and initially needed help with breathing, but then made a good recovery. When the baby was two days old, it tested positive for COVID-19.
“When it turned out that the baby had COVID-19, we started putting the puzzle together. We took additonal samples and analyzing began. A key question to answer was whether the virus was present in the placenta. We used different methods to examine it, including a standard PCR test. We also studied the placenta under a microscope where we clearly saw viral protein in all the areas of the placenta that were most affected. We could see that the placenta was infected on both the fetus’s and the maternal side,” says Zaigham.
The placenta was partially destroyed in its structure and did not work properly. “This may explain the baby’s low heart rate in the womb. We also took blood samples from the umbilical cord which showed a lower pH value than expected, which explains the baby´s lack of oxygen. Until two weeks before the mother fell ill, the fetus’s growth was normal and the routine check-ups did not show any infection. Therefore, we see a clear connection between the infection and the effect on the placenta,” says Zaigham.
COVID-19 present in the blood
Blood samples showed that the COVID-19 virus was also present in the mother’s blood, which is unusual.
“We then analyzed the virus strains in the baby, the mother and the placenta, and saw that they were almost identical. Since the mother and the baby had not been cared for together for the first 48 hours, the similarity of the virus strains was a strong indication that the baby was infected in the womb,” says Anna Holmberg, specialist in infectious disease medicine and hygiene care.
The baby developed its own antibodies
In accordance with hygiene routines, all staff who at any time were in close contact with the baby for the first 48 hours were tested for COVID-19 to rule out the possibility of the baby catching the virus from someone else. All were then monitored for 14 days to see if they developed symptoms.
“None in the staff tested positive and none did develop any symptoms while they were being monitored. This shows that the baby did not spread the infection to the care staff despite close contact and a high risk of virus exposure via droplet infection,” says Holmberg.
Another interesting discovery is that the baby developed its own antibodies.
“During the first year, children are usually dependent on antibodies from the mother, but here we were able to show that the baby formed its own antibodies against the COVID-19 virus. It is also good to know that the baby had a mild infection without any complications. However, it is somewhat worrying how the fetus was effected just before birth,” says Philip Tannenberg, doctor in pediatrics.
“We may have to rethink the monitoring of pregnant women who have COVID-19, and consider them as a more important risk group than we do today.”
Mehreen Zaigham believes that the study may have an impact on how people view pregnant women in relation to COVID-19.
“We have now seen that the placenta can be affected even thou the mother only has a mild infection, which in turn can lead to a lack of oxygen to the fetus in rare cases. We may have to rethink the monitoring of pregnant women who have COVID-19, and consider them as a more important risk group than we do today. If you have COVID-19 and have felt reduced fetal movements, you should absolutely seek care. And it is important that you follow the Swedish Public Health Agency’s recommendations,” she says.