The fact of ovarian reserve (OR) decreased in women with recurrent miscarriage has been well known. However, Whether OR would decrease with increasing numbers of previous miscarriages (PMs) is still unclear. To address this, OR parameters of following four groups’ patients were evaluated: 99 women with one previous miscarriage (PM1), 46 women with two previous miscarriages (PM2) and 35 women with three or more previous miscarriages (PM3). The control group included 213 women without a history of miscarriage (PM0). The correlation of OR parameters and the proportion of diminished ovarian reserve (DOR) patients between the four groups were analyzed using Kendall’s Tau-B coefficients. The results showed the median anti-Müllerian hormone (AMH) levels were 4.04, 3.40, 3.14 and 2.55 respectively in the PM0, PM1, PM2 and PM3 groups, respectively (H=15.99, P = 0.001); the median antral follicle counts (AFCs) were 10, 8, 8 and 6, respectively (H=24.53, P < 0.001); and the proportions of DOR patients were 10.8%, 15.2%, 23.9% and 31.4% (χ2 = 13.01, P = 0.005). In addition, AMH level and AFC correlated negatively with the number of PMs (correlation coefficients -0.154, P < 0.001; -0.205, P < 0.001 respectively), the proportion of DOR patients correlated positively with the number of PMs (correlation coefficients 0.156, P = 0.001). After stratification by age, AMH and AFC levels were still significantly lower in the PM3 group than the PM0 group (P < 0.05). The proportion of DOR patients between the PM0 and PM3 groups was statistically significant (P < 0.001). This study showed that AMH levels and AFCs decreased as well as the proportion of DOR patients increased significantly as the number of PMs increased. In conclusion, our study indicates decreased AMH levels and AFCs might be one of the factors contributing to early miscarriage.

Background Endometriosis affects many reproductive aged patients with fertility decline and poor outcomes of assisted reproductive treatments, mainly by decreased ovarian reserve and lower fertilization and implantation rates. In recent decade, altered oocyte microenvironments and abnormal spindle organization have been reported to be critical to oocyte chromosomal segregation, organization and aneuploid formation. However, clinical evidences are still limited on whether endometriosis influences oocyte and embryo development. We aimed to figure out the impact of endometrioma on embryo aneuploid formation. Method This retrospective cohort study included 1,021 patients (7,092 biopsied embryos) from January 2012 to December 2020. Fertile patients without a history of miscarriage who underwent PGT-M treatment with aneuploid screening were included. Patients with ovarian endometrioma were defined as the study group, while patients without endometriosis were defined as the control group. All demographic, controlled ovarian stimulation treatment and aneuploid screening data were recorded and compared. Results The incidence of endometrioma in our study population was 6.5%. There were 7,092 embryos biopsied in total, with 308 embryos in the study group and 6,784 embryos in the control groups. The demographic characteristics were comparable between the two groups except the basal FSH level (6.02 IU/L vs. 5.52 IU/L, p = 0.012). The euploid rate of the study group was significantly lower than that of the control group (52.6% vs. 61.8%, p = 0.012), while the oocyte maturation, fertilization, usable embryo and blastocyst formation rates were comparable. Adjusted for basal FSH level, starting stimulating gonadotropin dosage, total gonadotropin dosage and FSH level on hCG day, euploid rate was still negatively related to endometrioma status. Conclusions Endometrioma status disturbs oocyte and embryo development. For infertile patients with endometrioma who require assisted reproductive treatment, pre-treatment is necessary to improve treatment outcomes. Trial registration Not applicable.