The COVID-19 pandemic is the largest pandemic of an aggressive coronavirus in the human population in the 21st century. The pandemic may have a negative emotional impact on pregnant women, causing fear and stress. Negative feelings during pregnancy later affect fear of childbirth. Our study aimed to determine the relationship between fear of COVID-19, stress and fear of childbirth. We assume that fear of COVID-19 will be a mediator of the relationship between perceived stress and fear of childbirth. A total of 262 Polish pregnant women participated in this study. Perceived Stress Scale (PSS-10), Fear of COVID-19 Scale (FOC-6) and Labour Anxiety Questionnaire (KLP II) were used in the study. There was a statistically significant, moderate, and positive relationship between perceived stress, fear of COVID-19, and fear of childbirth. Fear of COVID-19 was a statistically significant mediator in the relationship between perceived stress and fear of childbirth. The COVID-19 epidemic may have a negative emotional impact on pregnant women, causing fear, stress and increased fear of childbirth. Childbirth during the COVID-19 pandemic is perceived by women as a threat to their well-being and health. Therefore, it is especially important to support a woman in the perinatal period and to enable her to give birth to a child.