Objective We aimed to investigate the incidence of adverse pregnancy outcomes including preterm birth, preeclampsia (PE), and fetal growth restriction (FGR) in pregnant women with COVID-19 according to the gestational age. Methods This retrospective study included 167 pregnant women who were hospitalized with confirmed COVID-19. The patients were divided into three groups according to the time of diagnosis as follows: <12 weeks of gestation (first trimester, n = 10), 12-24 weeks of gestation (n = 28), and >24 weeks of gestation (n = 129). Medical records of the patients were reviewed retrospectively and adverse pregnancy outcomes were analyzed. Results A total of 49 (29.3%) patients had an active COVID-19 infection at the time of delivery, while 118 (70.7%) gave birth after the infection was cleared. Twenty-three patients had preterm birth and the gestational age was <34 weeks in only four of these patients. There was no significant difference in the preterm birth, PE, FGR, HELLP syndrome, and gestational diabetes mellitus among the three gestation groups (p = 0.271, 0.394, 0.403, 0.763, and 0.664, respectively). Four (2.39%) patients required intensive care unit stay. Maternal death was seen in only one (0.59%) patient. Conclusion Our study showed no significant correlation between the gestational age at the time of COVID-19 infection and the frequency of adverse pregnancy outcomes such as preterm birth, PE, FGR, and gestational diabetes mellitus. However, further studies are needed to draw a firm conclusion on this topic.