Can pregnant women pass coronavirus onto their unborn baby?
There have now been several global reports of babies born to women infected with SARS-CoV-2, the virus that causes COVID-19. The vast majority of these babies have not tested positive for the virus or experienced any breathing problems.
There have now been a few case reports which appear to show that the infection can pass from the pregnant woman to the unborn baby, across the placenta. In one report from France, a baby was born to a woman who became ill with COVID-19 in late pregnancy. Placenta and newborn samples tested positive for the virus. The baby developed some neurological symptoms three days after birth, but recovered well and was discharged from hospital. In another US report, a pregnant woman with diabetes contracted COVID-19, and again placental samples tested positive. The baby tested positive for the virus 1-2 days after birth and showed mild breathing problems but made a full recovery.
Cases of the virus being passed from pregnant women to their unborn babies appear to be rare. These two cases excluded the possibility of transfer of the virus after birth but in other reports, without thorough testing, whether the infection was passed on in the womb or after birth is less clear. Reassuringly, there are no reports of a newborn baby becoming seriously unwell from COVID-19.
Where did the story come from?
The Guardian was one of several news outlets that reported on the case report from Paris, France, which was published in the peer-reviewed science journal Nature Communications in mid-July. Around the same time, Science News also reported a case in Texas, US.
What is the basis for the claim?
The French study reports that a woman 35 weeks’ pregnant was admitted to hospital with breathing difficulties and tested positive for SARS-CoV-2. The baby boy was delivered by caesarean, and doctors took samples from the placenta and amniotic fluid surrounding the baby. They also tested the baby’s blood and fluid from his lungs when his breathing tube was removed. All samples tested positive for SARS-CoV-2 infection.
Although the baby did not seem unwell at first, three days after birth he developed symptoms of irritability, poor feeding and muscle spasms. A brain scan showed possible signs of inflammation, but samples of the fluid that surrounds the brain and spinal cord were negative for SARS-CoV-2 or other infective microorganisms. The baby received no specific treatment and recovered over the next few days.
In another US report, a pregnant woman positive for COVID-19 delivered prematurely at 34 weeks due to pregnancy complications of her diabetes. The placenta tested positive for SARS-CoV-2, though the baby girl was healthy. She did not test positive until 1-2 days after birth when she also developed mild breathing problems. She received oxygen but didn’t need ventilation, and made a full recovery.
Case studies only tell us about single incidents, which may be rare. We do not know how many pregnant women, globally, have tested positive for COVID-19 at the time of delivery. Of them, we do not know what proportion of their newborns have also tested positive. These results show that the infection can be transferred across the placenta, though in other cases it has been difficult to know whether the infection was transferred in the womb or passed from mother to baby after birth. Regardless of the route of transmission, the main point is that all babies infected with COVID have made a full recovery.
What do trusted sources say?
The NHS website has useful information about COVID-19 and pregnancy. It states: ‘It may be possible for you to pass coronavirus to your baby before they are born. But when this has happened, the babies have got better. There’s no evidence coronavirus causes miscarriage or affects how your baby develops in pregnancy.’
Analysis by EIU Healthcare, supported by Reckitt Benckiser
- Vivanti, A.J., Vauloup-Fellous, C., Prevot, S. et al. Transplacental transmission of SARS-CoV-2 infection. Nat Commun 11, 3572 (2020). https://doi.org/10.1038/s41467-020-17436-6
- Pregnancy and coronavirus. NHS.UK website https://www.nhs.uk/conditions/coronavirus-covid-19/people-at-higher-risk/pregnancy-and-coronavirus/ (Accessed 17 August 2020)