Comparison of the etiological composition between recurrent implantation failure and recurrent pregnancy loss

Objective To explore the differences of etiology of recurrent implantation failure （RIF） and recurrent pregnancy loss （RPL）. Methods Patients with RIF （<i>n = </i>315） and patients with RPL （<i>n = </i>376） admitted to the Reproductive Center of the First Affiliated Hospital of Sun Yat-sen University from June 2018 to June 2021 were included. General and etiological data were collected to compare the differences in baseline data and etiological composition. Relative risk factors of the etiology of these two conditions were identified by multivariate regression analysis. Results Univariate analysis showed a significantly higher proportion of chronic endometritis， endometrial polyps， endometriosis， endometriosis complicated with polyps， diminished ovarian reserve and a significantly lower proportion of unexplained cause in the RIF group than in the RPL group （all <i>P &lt;</i>0.05）. Multivariate logistic regression analysis showed that the incidence of chronic endometritis （OR=3.044， 95%CI 1.849-5.011， <i>P &lt; </i>0.001）， endometrial polyps （OR=3.769， 95%CI 1.670-8.510， <i>P &lt; </i>0.001）， endometriosis （OR=3.812， 95%CI 2.131-6.819， <i>P &lt; </i>0.001） and diminished ovarian reserve （OR=2.175， 95%CI 1.285-3.683， <i>P = </i>0.004） in the RIF group was significantly higher than that in the RPL group. The proportion of patients with lower anti-Mullerian hormone levels （OR=0.917， 95%CI 0.864-0.973， <i>P = </i>0.004） in the RIF group was higher compared with that in the RPL group. Conclusion Chronic endometritis， endometrial polyps， endometriosis， decreased anti-Mullerian hormone level and diminished ovarian reserve are more common in RIF patients， and the screening and monitoring of the above lesions should be strengthened in the subsequent practice of assisted reproduction.