If a pregnant woman gets Covid, how does that affect the cord blood?

01 Would pregnant women infect their fetus?

 

First of all, no evidence suggests that Covid can get through the placental barrier and infect the fetus. [1] This protection also applies to the cord blood as a part of the fetus.

On Dec. 13, 2022, in response to the question as to whether Covid-infected pregnant women will pass on the virus to the fetus, Qiao Jie, president of Peking University Third Hospital and a member of the Chinese Academy of Engineering, commented that since the placenta acts as a very good protective barrier, it is almost impossible for the fetus to get infected. [2]

For the Covid virus to gain entry into cells, its viral key needs to find two fitting locks: angiotensin-converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2). The placenta, however, has extremely low co-expression levels of these two proteins, which may explain the protective effect that the placenta can play. [1]

 

02 Cord blood

 

Before the delivery, the cord blood is still a part of the fetus’s body, and so is also protected by the placenta.

A study published in The Lancet in March 2020 found that Covid was not detected in cord blood, amniotic fluid, pharyngeal swabs or patients' breast milk from 6 newborns.

 

 

 

In another systematic review, scientists analyzed the delivery of a total of 310 pregnant women infected with Covid and concluded that no vertical transmission occurred. These studies used nucleic acid test results as a basis and were not affected by contamination, compared to other studies which used nasopharyngeal swabs of newborns and IgG antibodies. [4]

 

03 Antibody protection

 

In fact, more than 90% of infected pregnant women recover before delivery, [1] whose bodies will retain the protective antibodies against the Covid for some time.

And the placenta has truly amazing abilities that not only protects the fetus from the Covid, but also allows IgG antibodies from the mother to enter the fetus’s bloodstream.

 

 

Infant immunity against viral infections is advanced by the placenta-dependent vertical transfer of maternal antibodies [5]

In January 2021, a study published in JAMA Pediatrics showed that 83 mothers carried Covid antibodies at the time of delivery, and IgG antibodies were detected in cord blood from 72 of the 83 newborns, while no IgM antibodies were detected. Therefore, these newborns acquired passive immunity through the antibodies from their mothers. [6] 

 

04 Transmission through blood transfusion

 

The donated cord blood will eventually be used as blood products in a clinical setting. The question is: could blood products transmit Covid?

 

 

 

The American Association of Blood Banks (AABB) has stated that individuals are not at risk of contracting Covid through blood donations or transfusions since respiratory viruses are not normally transmitted through blood donations or transfusions. The U.S. Food and Drug Administration (FDA) also reported that there have been no reported or suspected cases of Covid transmission through blood products to date. In addition, no cases of transmission via blood transfusions have been reported for the other two coronaviruses that have emerged in the past 20 years (SARS and MERS). [7]

In December 2022, the National Health Commission also clarified on Health China Weixin public account: "Covid is a respiratory virus and is not transmitted through blood transfusion. Globally, there have been no reports of covid transmission through blood transfusion."

 

Reference · Literature

1. UpToDate.com

2. Weibo account of Xinhua Agency

3. Chen H, etc. Clinical characteristics and intrauterine vertical transmission potential of COVID-19 infection in nine pregnant women: a retrospective review of medical records. The Lancet 2020; 395:809-815.

4. Huntley BJF, etc. Rates of maternal and perinatal mortality and vertical transmission in pregnancies complicated by severe acute respiratory syndrome coronavirus 2 (SARS-Co-V-2) infection: a systematic review. Obstet Gynecol. 2020;136:303–12.

5. Marie Albrecht, Mirja Pagenkemper, etc, Infant immunity against viral infections is advanced by the placenta-dependent vertical transfer of maternal antibodies, Vaccine,Volume 40, Issue 11,2022,Pages 1563-1571

6. Flannery DD, Gouma S, Dhudasia MB, et al. Assessment of Maternal and Neonatal Cord Blood SARS-CoV-2 Antibodies and Placental Transfer Ratios. JAMA Pediatr. 2021;175(6):594–600. doi:10.1001/jamapediatrics.2021.0038

7. AABB.org

8. Health China Weixin public account, 2022-12-24: Does blood donation increase the risk of contracting Covid? Can I still donate after infection? Will it have a negative impact on the body? Here are the official answers!