Abstract: Objective To investigate the clinical value of CD38 expression in endometrium in patients with infertility or embryo implantation failure before embryo transfer. Methods A total of 145 cases of CD138 and CD38 positive endometrium patients were selected from in vitro fertilization or intracytoplasmic sperm injection-embryo transfer(IVF/ICSI-ET)in the Reproductive Medicine Center of General Hospital of Ningxia Medical University during Sep. 2019 and May 2022. The patients were divided into treatment group and control group according to whether they received anti-inflammatory treatment. The positive rate of CD138 and CD38 was fitted by smooth curve with continuous pregnancy rate as index. According to CD38=10%/HPF value to cut-off, the patients were divided into mild chronic inflammation group(CD38<10%/HPF)and severe chronic inflammation group(CD38≥10%/HPF). The effects of anti-inflammatory therapy on the pregnancy outcomes in patients with different levels of inflammation were compared. With continuous pregnancy as the primary endpoint, relevant factors were analyzed with multiple Logistic regression. Results In the mild chronic inflammation group, there were no significant differences in age, body mass index(BMI), anti-Mullerian hormone(AMH), basal follicle-stimulating hormone(bFSH), infertility duration, embryo transfer type, intimal thickness on the day of transfer and embryo age between the treatment group(n=77)and control group(n=17)(P>0.05), but there was significant difference in the number of transferred embryos between the two groups(P<0.05). Single embryo transfer was adopted in the treatment group. There were no significant differences in embryo implantation rate, biochemical pregnancy rate, clinical pregnancy rate, early abortion rate and continuous pregnancy rate between the two groups(P>0.05). In the severe chronic inflammation group, there were no significant differences in age, BMI, AMH, bFSH, duration of infertility, type of embryo transfer, intimal thickness on the day of transfer, embryonic age of transferred embryos and number of transferred embryos between the treatment group(n=33)and control group(n=18)(P>0.05). The embryo implantation rate(50% vs 22.22%, P=0.021)and sustained pregnancy rate(54.54% vs 22.22%, P=0.039)in the treatment group were significantly higher than those in the control group. The clinical pregnancy rate of the treatment group was higher than that of the control group(60.6% vs 33.33%, P=0.083), and the early abortion rate was lower(5% vs 33.33%, P=0.123), but the differences were not statistically significant(P>0.05). Multivariate Logistic regression analysis showed that anti-inflammatory therapy before transplantation had no significant effects on the duration of pregnancy in mild chronic inflammation patients, but was a protective factor for the duration of pregnancy in severe chronic inflammation patients(P=0.020, OR=4.705, 95%CI=1.284-17.572). Conclusion It may be more reasonable to use endometrial CD38 positive 10%/HPF to distinguish the degrees of chronic endometritis and to guide pre-transfer anti-inflammatory therapy. When chronic endometritis is mild, anti-inflammatory treatment has no significant effects on the pregnancy outcomes; when chronic endometritis is severe, the pregnancy rate shows a downward trend. Anti-inflammatory therapy may reverse the adverse pregnancy outcomes and improve pregnancy outcomes after embryo transfer.

Key words: Chronic endometritis, CD38, Anti-inflammatory therapy, Embryo implantation, Pregnancy outcome