Maternal Risk Factors
Pregnant women are usually considered a high-risk group for viral
infections, such as SARS-CoV-2. The pregnancy induces physiological
immunosuppression in women, making the mother more vulnerable to severe
infections. The anatomical changes in mothers such as an increase in the
transverse diameter of the thoracic cage and an elevated level of the
diaphragm decreases maternal tolerance to hypoxia. The changes in lung
volume and physiological vasodilation can lead to mucosal edema and
increased secretions in the upper respiratory tract. In addition,
alterations in cell-mediated immunity contribute to the increased
susceptibility of pregnant women to be infected by intracellular
respiratory pathogens like COVID-19 and cause severe pneumonia14,
18-20.
This immunosuppressive alteration in pregnancy may result due to the
attenuation in cell-mediated immunity by Th1 cells due to the
physiological shift to a Th2 dominant environment, which contributes to
overall infectious morbidity by increasing maternal susceptibility to
intracellular pathogens like viruses. However Dashraath et al postulated
that changes in the hormonal levels during pregnancy which influence
immunological activity against viral pathogens, in addition to
physiological shift to a predominant Th2 response, may favor the
expression of anti-inflammatory cytokines (IL-4 and IL-10) and other
unknown immune adaptations which may serve as the predominant immune
response to SARS-CoV-2, thereby resulting in a lesser severity of COVID-
19 infection as compared to the non-pregnant cohort.21-23.
Changes in the cardiovascular and respiratory systems, including
increased heart rate, stroke volume, oxygen consumption, and decreased
lung capacity, as well as the development of immunologic adaptations
that allow a mother to tolerate an antigenically distinctive fetus,
increases the risk for pregnant women to develop severe respiratory
disease. It is significant that these co-morbid maternal conditions,
which included preeclampsia, pregnancy-induced hypertension, uterine
scarring, gestational diabetes, and uterine atony, does not appear to be
significant risk factors for intrauterine transmission of SARS-CoV-2 to
the fetus 17.