Authored by: Venkat Rao
SARS-CoV-2 virus, among others is a teratogenic pathogen. A team of Brazilian investigators report remarkable findings of neurological impairment in infants exposed to SARS-CoV-2 through maternal infection. Researchers employed a prospective approach consisting of a cohort of sixty-nine babies exposed to SARS-CoV-2 virus during pregnancy and a control group of sixty-eight unexposed babies. Study group mothers were lab-confirmed cases for COVID-19 infection and both study and control group mothers were unvaccinated. Infants were monitored for
neurodevelopment for all activities related to normal development as scored according to the World Health Organization’s Integrated Management of Childhood Illness Guidelines. At 12 months, 20 percent of infants exposed in uterus to COVID-19 virus compared to about 6 percent of infants in the control group demonstrated neurodevelopmental delays. Worsening of the fine motor functions impairment and personal-social scores were the most notable developmental delays observed at 12-month evaluation among the infants exposed in utero to COVID-19 virus. Head ultrasound imaging indicated abnormalities in 10 percent of the exposed infants with no similar observations in the control group.
By definition, teratogenic pathogens are viruses or bacteria that cause physical and/or mental defects during pregnancy through a direct effect on the fetus. The developmental abnormalities could be physical, mental or both, leading to severe birth defects, and in other cases lead to embryonic or fetal death. Â
A growing fetus exposed to teratogenic pathogens from mother’s infection leading to injury and developmental abnormalities is well documented in the published medical literature. Developmental effects due to in-utero exposure of the fetus to material infection are attributed to injury of the placenta leading to fetal growth restriction and developmental abnormalities. A well-known group of pathogens, collectively known as TORCH, consisting of Toxoplasma gondii, others like Treponema pallidum, rubella virus, cytomegalovirus, and herpes simplex virus, and zika virus (flavivirus) are teratogenic virus inducing developmental abnormalities in the infants exposed in-utero to maternal infection. Pregnant women infected with teratogenic viruses are susceptible to placental damage inducing inflammation caused by these pathogens that disrupt fetal development of the lungs, and brain.
A notable characteristic is that human placenta functions as a barrier for viruses to cross and enter the fetus. That does not mean the growing fetus is completely protected from infectious pathogens. If, and when a teratogenic virus cross over and reach the fetus, it could result in severe birth defects such as microcephaly or even fetal death.
A well-known example is the Zika infection during pregnancy was associated with adverse outcomes including microcephaly, a birth defect where the newborn baby’s head is much smaller than normal size. The teratogenic virus, in this case the Zika virus, causes abnormal head growth, or stopped growing due to exposure to the virus. A baby with microcephaly suffers life-long without a cure from intellectual disability, speech delay, seizures, and abnormal muscle functionality. Most microcephaly cases occurred. when exposure was during the first trimester of pregnancy.
How does SARS-CoV-2 cause birth anomaly?
Researchers reported Delta variant of SARS-CoV-2 virus causing pregnancy complications including stillbirths. Analysis of blood and placental samples revealed presence of Delta variant of SARS-CoV-2 virus in pregnant women with COVID-19. US Centers for Disease Control and Prevention (CDC) issued a report in November 2021 that pregnant women with COVID-19 were four times likelier to have miscarriages, resulting in the death of a fetus after 20 weeks of pregnancy, than uninfected pregnant women during period when Delta variant of the virus was the cause for a majority of COVID-19 infections in the United States. According to the CDC study of 1,249,634 delivery hospitalizations during March 2020 to September 2121, the risk of stillbirth increased among women with COVID-19 and the magnitude of association between COVID-19 during pregnancy and stillbirths was higher during the Delta-phase of the pandemic.
A growing body of research has linked the Delta variant of SARS-CoV-2 with increased risk for teratogenic effects, pregnancy complications, including stillbirths. These studies have suggested two likely pathways for teratogenic viral infection during pregnancy causing developmental damage to the fetus. The first pathway involve infection resulting in damages to the maternal-fetal placental interface altering transfer of critical nutrients and other growth factors to the growing fetus leading to miscarriage, growth restrictions, severe birth defects such as microcephaly and even fetal death.
The other pathway involve inflammatory response by the growing fetus to the infection resulting in organ damage, developmental abnormalities, and fetal death. COVID-19 global pandemic created a vast global exposure scenario of pregnant women to various strains of SARS-CoV-2 that is yet to be quantified to assess the multi-generational impact of the pandemic.
Although much of the focus on COVID-19 remain on the short-term, mostly reversible adverse outcomes, of the infectious disease, developmental abnormalities are irreversible and will persist through the next generation as lingering marker of the public health catastrophe caused by the global pandemic.