PREGNANCY AND DELIVERY OUTCOMES AFTER FRESH AND FROZEN-THAWED EMBRYO TRANSFER: EXPERIENCE FROM A SINGLE PERINATAL CENTER

Abstract

Summary. Aim. To evaluate and compare pregnancy and delivery outcomes following fresh and frozen embryo transfer in women treated for infertility at the Reproductive Medicine Centre of the Hospital of Lithuanian University of Health Sciences Kauno klinikos and who subsequently gave birth at Kauno klinikos. Methods. A retrospective tudy was conducted in the Department of Obstetrics and Gynecology at the Hospital of the Lithuanian University of Health Sciences, Kauno Klinikos. The study included women who delivered at Kauno Klinikos and underwent assisted reproductive technology procedures at the Reproductive Medicine Centre between September 1, 2019, and January 1, 2024, resulting in either fresh or frozen embryo transfer. The participants were divided into two groups according to the type of embryo transfer: group I included cases of fresh embryo transfer, and group II included cases of frozen-thawed embryo transfer. Pregnancy, delivery, and neonatal outcomes were analyzed. Statistical analysis was performed using IBM SPSS Statistics 31. Differences were considered statistically significant at p < 0.05. Results. After analyzing 156 cases of pregnancy and delivery following the transfer of either fresh embryos (n = 45) or thawed blastocysts (n = 111) into the uterus, the groups were found to be homogeneous with respect to key sociodemographic parameters. Assessment of clinical characteristics revealed a higher prevalence of thyroid disease in group II (p = 0.025). There were no statistically significant differences between the groups regarding mode of delivery (p = 0.089), the distribution of cesarean section indications, frequency of labor induction (p = 0.065), or incidence of pregnancy complications (p > 0.05). Although no significant difference was observed in the overall rate of preterm births between the study groups (p = 0.778), very early preterm deliveries (< 32 weeks) were more frequently registered in group I (p = 0.022). No statistically significant differences were found between groups regarding neonatal birth weight (p = 0.998), Apgar scores at 1 and 5 minutes (p = 0.549 and p = 0.754, respectively), incidence of macrosomia (p = 0.444), or the need for neonatal intensive care (p = 0.191). Conclusions. No statistically significant differences were found in pregnancy complications, delivery outcomes, or neonatal outcomes between pregnancies achieved after fresh embryo transfer and those achieved after frozen-thawed embryo transfer. Although the overall rate of preterm birth was similar between the study groups, very preterm births (< 32 weeks ogestation) occurred more frequently following fresh embryo transfer.