Epidemiological Survey and Risk Factor Analysis of Recurrent Spontaneous Miscarriages in Infertile Women at Large Infertility Centers

BACKGROUND A higher frequency of spontaneous miscarriage has been observed in infertile couples, and there is a higher prevalence of infertility among patients with a history of recurrent spontaneous miscarriages (RSMs; ≥2 miscarriages). This study aimed to determine the proportion of infertile patients with RSM and examine risk factors associated in patients with RSM being treated with assisted reproductive technologies. METHODS This cross-sectional observational study was conducted at six reproductive medicine centers in three cities of China. Data of 751 patients with at least one spontaneous miscarriage were analyzed. Demographic data and etiological factors associated with infertility were compiled and compared between patients with a single spontaneous miscarriage (SSM) and those with RSM. RESULTS Two hundred (26.6%, 95% confidence interval [CI]: 23.50-29.95%) patients experienced RSMs and 551 (73.4%) had a single miscarriage. The odds of RSM increased with increasing age (odds ratio [OR] = 1.06), uterine disorders (OR = 2.09), endocrine disorders (OR = 2.48), and immune disorders (OR = 2.98). Higher education level, masters or above, and a pelvic cavity disorder were associated with lower risk of RSM (OR = 0.27 and 0.46, respectively). Late spontaneous miscarriages were more frequent in patients with RSM than in those with a SSM (31.5% vs. 14.2%, respectively, P< 0.001) and were associated with a history of uterine cavity procedures (OR = 2.095) and cervical factors related to infertility (OR = 4.136, 95% CI: 1.012-16.90). CONCLUSIONS Compared to patients with only a SSM, the conditions of patients with RSM are more complicated. To increase the success rate of assisted reproductive technology, factors including uterus cavity adhesion, cervical relaxation, endocrine disorders, and immune disorders should be treated before assisted reproduction is initiated. These data may provide treatment guidance for infertile patients with a history of RSM.