Background: The hypoxia-inducible factors (HIF) are considered master regulators of oxygen homeostasis and are oxygen level sensitive. Currently, there is no information regarding the expression of HIF-1α in pregnant women with COVID-19 infection and its potential involvement in the placentation of this condition. Objective: The current study aims to detect the expression of HIF-1α and possible molecular link between the expression of HIF-1α and PLGF. Methodology: A case-control study was conducted in a tertiary university hospital between January and September 2022. Placental tissue of post COVID-19 infected pregnant women (n= 34) and healthy control (n=16) were collected and processed for gene expression of HIF-1α and PLGF by Quantitative real-time PCR.

Results: There was a statistically significant higher median level of HIF-1α among cases compared to controls (P<0.001). Moreover, there was a statistically significant higher median level of PLGF among cases compared to controls (P<0.001). There was statistically significant moderate positive correlation between HIF-1α and PLGF gene (r=0.636, P <0.001) among studied samples, however no statistically significant correlation between the two genes among cases and controls groups separately.

Conclusion: the higher levels of HIF-1α and PLGF in the placentas of post COVID-infected pregnant women compared to normal pregnant women indicate that COVID-19 hypoxia did not affect the process of placentation. This is confirmed also by the positive correlation between HIF-1α and PIGF in placental tissues among total studied samples.