Background: During the pandemic, Favipiravir, an oral antiviral agent, was used for COVID-19 treatment. However, its safety profile for pregnant women, especially during the second and third trimesters, is not well-established.

Objective: To assess the pregnancy outcomes and risk of congenital anomalies associated with favipiravir exposure during the second and third trimesters in COVID-19-infected pregnant women.

Materials and Methods: A retrospective cohort study was conducted at the Department of Obstetrics and Gynecology, Queen Savang Vadhana Memorial Hospital, including pregnant women beyond 14 weeks gestation who delivered between June 1, 2021, and May 31, 2022. Participants were divided into those exposed to favipiravir, which were 99 patients, and those who were not exposed, which included 115 patients. Data on maternal, obstetric, and neonatal outcomes were collected and analyzed.

Results: Out of 383 registered COVID-19-infected pregnant women, 214 were included in the analysis. No severe maternal drug reactions were observed. Favipiravir exposure was significantly associated with an increased rate of small for gestational age (SGA) infants at 13.1% versus 3.5% (OR 4.16, p=0.01). No significant differences were found in other obstetric and neonatal outcomes, including preterm delivery, cesarean delivery, or neonatal morbidity. Specific congenital anomalies such as cardiac defects and renal pyelectasis were observed in the favipiravir-exposed group, but these were not statistically significant.

Conclusion: Favipiravir exposure during the second and third trimesters was associated with an increased risk of SGA, while congenital anomalies and other perinatal outcomes did not differ significantly between groups.

Received 28 November 2024 | Revised 18 February 2025 | Accepted 2 April 2025

DOI: 10.35755/jmedassocthai.2025.6.431-439-01780