Problem We aimed to investigate the main causes of recurrent miscarriage (RM) in patients with losses after spontaneous gestation (SG) and after in vitro fertilization (IVF). Method of Study A prospective case‐control study was conducted. The eligible patients were women who had experienced two or more consecutive abortions after <12 weeks’ gestation, two consecutive losses after SG, or two consecutive losses after IVF. All patients were subjected to the following evaluations: karyotyping of the aborted material, alloimmune and autoimmune marker testing, and acquired and hereditary thrombophilia marker testing. Results In total, 58 patients were eligible: 32 patients with RM after SG and 26 patients with RM after IVF. The factors associated with RM were genetic (29%), immune (14%), thrombophilic (21%), and thrombophilic and immune (24%), and only 12% of the cases were idiopathic. Comparing the two study groups (SG and IVF), all studied factors were similar, except for a higher ANA positivity observed in the SG group (SG 30.4% vs IVF 5.3%, OR 8.6 (CI 1.1‐21.1, P .048). Conclusion Our study identified the possibly factors associated with recurrent miscarriage in 86% of the cases, and these factors appear to be similar in patients with recurrent miscarriage after spontaneous gestation and IVF. This study demonstrates that IVF with PGT‐A with euploid embryo transfer could reduce abortions by up to 29%, but other factors need to be investigated even in patients undergoing in vitro fertilization.