Abstract Study question What are the risk factors for early pregnancy loss (EPL) in infertility patients undergoing in vitro fertilization-embryo transfer (IVF-ET) cycles? Summary answer The risk factors for EPL were maternal age, 14-day β-human chorionic gonadotrophin(β-hcg) levels and cycle type. What is known already Pregnancy obtained through assisted reproductive technology still has a high risk of spontaneous early pregnancy abortion, and the cause of which is unclear. It not only affects the rate of ongoing pregnancy and live birth, but also increases the psychological and economic burden of patients. At present, there have been many studies on the risk factors of early pregnancy loss in IVF/ICSI-ET at domestic and overseas, but the results are different, which may be related to the selection of different research objects, sample size and statistical methods. Study design, size, duration A retrospective study of 6107 embryo transfer cycles collected from January 2018 to December 2018 was performed. The cycles were divided into the EPL group (n = 987) and the live birth group (n = 5120) according to the cycle outcomes. Participants/materials, setting, methods Baseline data and clinically relevant indicators were compared between the two groups, including maternal age, infertility years, infertility type, body mass index (BMI), tubal factor, ovulatory dysfunction, endometriosis, male factor, antral follicle count (AFC), single gene related genetic disease, follicle-stimulating hormone (FSH), estradiol (E2), luteinizing hormone (LH), 14-day β-hcg levels, prolactin (PRL), progesterone (P), testosterone (T), anti-Müllerian hormone (AMH), cycle type and the number of transplanted embryos. Main results and the role of chance The EPL rate of the infertility patients undergoing fresh/frozen-thaw embryo transfer cycle was 16.16%. Univariate analysis showed that there were statistically significant differences between the two groups in maternal age, AFC, 14-day β-hcg levels, T, AMH, infertility years, cycle type, infertility types, chromosome disease and male factors (P < 0.05). The results of binary logistics regression analysis showed that maternal age, 14-day β-hcg levels and cycle type were related factors to EPL (P < 0.05). Limitations, reasons for caution This study lacked some baseline data, such as adverse pregnancy history, abortion history, and previous transplant failure history, and male factors such as BMI, age, semen results, smoking history. The information about fetal chromosomes was also missing. Wider implications of the findings Clinical prevention and treatment of risk factors can be targeted to improve pregnancy outcomes after transplantation. Trial registration number none