#17 : Clinical Efficacy of IVIG Depending on the Peripheral Blood NK Cell Proportions in Women with Recurrent Pregnancy Loss

Abstract

Backgrounds and Aims: Etiology of repeat pregnancy loss (RPL) is complex, approximately 50% of cases of RPL had been classified as unexplained. Nowadays, elevated peripheral blood NK cell proportions are supposed to be related to RPL, and IVIG could down-regulate the NK cell levels. However, the efficacy of IVIG in RPL women is still under debates. The aims of this study were to evaluate the clinical outcomes of IVIG in RPL women with elevated peripheral blood NK cell proportions (PbNK), and to analyze the efficacy depending on the levels of PbNK. Methods: In this retrospective study, 916 women suffered two more miscarriages were evaluated from Jan. 2002 to Aug. 2022. After excluding the genetic, anatomic, endocrinologic causes and antiphospholipid antibody syndrome, 383 unexplained RPL women with elevated PbNK were enrolled. IVIG were treated 400 mg/kg in every three weeks, started right after a positive pregnancy test. Clinical pregnancy outcomes and miscarriage were evaluated. Results: Mean age of enrolled women was 35.24±4.31 years old, mean parity was 0.15±0.36 and mean number of miscarriages was 2.79±1.46 (min 2–max 14). Mean PbNK was 17.74±5.82 (12.0–45.3%). During the IVIG infusion, no serious side effects were found. Among 238 pregnant women, 48 women suffered miscarriage unfortunately. Excluding the termination cases related with chromosomal abnormality and congenital anomalies, live birth rate was 80.9%. In 4 subgroups (NK<15%, 15–20%, 20–25%, <25%), the live birth rates tended to decrease as the PbNK increased, statistically insignificant (84.0%, 82.1%, 72.5%, 65.0%). Mean gestational weeks (GW), preterm birth rates under 37th GW and preterm birth rates under 34th GW were similar in each group. Conclusion: IVIG treatment in RPL women with elevated peripheral blood NK cell proportions could be beneficial without serious side effects. Even in higher elevated level of NK cell proportion, it could be effective as well.