Objective - To analyze the effectiveness of minimal stimulation protocol of IVF treatment for patients with severe diminished ovarian reserve (DOR), especially for whom failed with several cycles of conventional stimulation IVF protocols previously. Design, setting and sample – A single center retrospective cohort study of undergoing IVF during January 1st, 2005 to December 31st, 2021. A total of 1,111 conventional stimulation cycles and 14,139 cycles of minimal stimulation IVF cycles were analyzed. Methods - Women who had undergone minimal stimulation protocol for IVF treatment and who met the study design were admitted to the study. Patients who met the study design undergone conventional stimulation IVF cycles were also included as control. Basic characteristics and clinical outcomes were all recorded and matched for the analysis of the effectiveness of minimal stimulation IVF treatment. Main Outcome Measures – The number of oocytes retrieved, the number of embryos obtained and gonadotrophin stimulation dosage, stimulation days and clinical pregnancy rates were analyzed. Results - In 16 years, a total of 14,139 cycles of minimal stimulation IVF cycles were included into this study in order to compare the effectiveness of the minimal stimulation cycles and the conventional stimulation cycles. Although a smaller number of oocytes was retrieved in the minimal stimulation cycles compared with the conventional stimulation cycles (1.39 vs 2.26, p<0.05), the similar pregnancy rates were obtained in both groups (16.93% vs 18.99%). There were also no differences in live birth and miscarriage rates in the minimal stimulation cycles compared with the conventional cycles. Further analysis indicates that the clinical outcomes were reduced significantly after two cycles of conventional stimulation cycles with high dosage of gonadotropins in those women with DOR. Conclusion- Cumulative minimal stimulation IVF treatment is an effective alternative for women with severe DOR. If a woman with DOR is seeking fertility treatment, it is wise to turn to minimal stimulation protocol after no more than two cycles of the conventional stimulation.

Premature ovarian insufficiency (POI) refers to women premature amenorrhea before the age of 40, elevated levels of follicle stimulating hormone (FSH). In clinic, the etiology of POI remains unknown in most patients. In this study, seventy-four Chinese Han women with idiopathic POI were collected to analyze the genetic etiology. Triplet repeat-primed polymerase chain reaction (TP-PCR) was performed to screen the FMR1 (CGG)n premutation, and then 60 POI related genes were sequenced by targeted next generation sequencing (NGS) in POI patients with normal FMR1. One patient (1/74) with FMR1 premutation was identified. Targeted NGS revealed that 15.07% (11/73) patients had pathogenic or likely pathogenic variants of Mendelian genes (FOXL2, EIF2B2, CYP17A1, CLPP, MCM9, GDF9, MSH5, ERCC6, POLG). Ten novel variants in six Mendelian genes were identified, such as CLPP c.355A>C (p.I119L) and c.688A>C (p.M230L), MCM9 c.1157C>T (p.T386M) and c.1291A>G (p.M431V), GDF9 c. 238C>T (p.Q80X), MSH5 c.604G>C (p.G202R) and c.2063T>C (p.I688T), ERCC6 c.C1769C>T (p.P590L), POLG c.2832G>C (p.E944D) and c.2821A>G (p.I941V). This study enriched the variant spectrum of POI related genes and suggested targeted NGS was an efficient and optional further clinical test for POI patients without FMR1 premutation.