Increased serum IL-12 levels are associated with adverse IVF outcomes

Interleukin-12 (IL-12) is involved in the occurrence and development of many diseases, such as preeclampsia, intrauterine growth restriction, preterm labor, and recurrent pregnancy losses. This study aimed to determine whether a high serum level of IL-12 was associated with adverse in vitro fertilization (IVF) outcomes. Included infertile women with high serum IL-12 levels who underwent IVF cycles and infertile controls with pure tubal etiology. The impact of serum IL-12 on baseline and clinical characteristics, immune-related indicators, IVF laboratory, and pregnancy outcomes were compared. In addition, the correlation of follicular fluid IL-12 and serum IL-12 level and the role of IL-12 in apoptosis of granulosa cells (GCs) was investigated. Women with high serum IL-12 levels had lower numbers of retrieved oocytes, embryos, perfect and available embryos, lower rates of perfect and available embryos, and blastocyst formation. Additionally, significantly higher levels of serum Th1, Th2, and Th17-related cytokines were observed in women with high serum IL-12 levels than in the controls. Meanwhile, the follicular fluid IL-12 levels were positively correlated with serum IL-12 levels, and IL-12 promoted apoptosis of GCs in vitro. We concluded that women with serum high IL-12 levels may have adverse IVF outcomes, partly by promoting apoptosis of GCs. Therefore, early screening for cytokines, especially IL-12, and appropriate consultation for couples receiving IVF-ET should be considered. In addition, specific immune and inflammatory mechanisms associated with high serum IL-12 levels should be further explored.