To investigate the clinical characteristics and pregnancy outcomes of patients who underwent in vitro fertilization-embryo transfer for assisted conception combined with subchorionic hematoma (SCH).

A retrospective analysis was conducted on 79 patients diagnosed with SCH who underwent IVF-ET at Sun Yat-sen Memorial Hospital, Zhongshan University, from January 2021 to May 2023.Grouped by pregnancy outcome, general clinical data, hematoma and pregnancy-related data, and laboratory indexes were compared in the pregnancy loss group (13 cases) and the live birth group (66 cases). The group was divided into an early miscarriage group (11 cases) and a group without early miscarriage (68 cases), using whether or not the pregnancy had reached 12 weeks as the timeline. Among 79 patients, a total of 71 obtained detailed data that can calculate the hematoma/gestational sac volume ratio. The hematoma/gestational sac volume ratio was used as a subgroup to analyze the pregnancy outcomes and past medical history of small hematoma (37 cases), medium hematoma (9 cases) and large hematoma (25 cases) patients.

The hematoma/gestational sac volume ratio was greater in the early miscarriage group than in the group without early miscarriage (2.83 vs 0.13, Z=-3.147), the gestational week of diagnosis of subchorionic hematoma was earlier than in the group without early miscarriage (6.1 vs 8.0 weeks, t=-2.266), and the body mass index was lower than in the group without early miscarriage (19.5 vs 21.7, t=-2.202), and the differences were statistically significant (P<0.05). Grouped by hematoma/gestational sac volume ratio, the pregnancy loss rate was significantly higher in the large hematoma group than in the small and medium hematoma groups (32.0% vs 5.4%, 22.2%, χ²=4.480), and the differences were statistically significant (P<0.05); the number of previous late miscarriages and induced abortions affected the size of SCH. The pregnancy loss group had higher levels of B-lymphocytes (19.0% vs 15.7%, t=2.007), higher anti-β2 glycoprotein antibody IgG type (5.1 U/ml vs 2.37 U/ml, Z=-2.075), higher levels of complement C3(1651.2 mg/L vs 1087.8 mg/L, t=2.128), and lower levels of complement C4(196.0 mg/L vs 231.5 mg/L, Z=-2.106) compared with the live birth group, and the differences were statistically significant (P<0.05). Coagulation indices were within the normal range in the pregnancy loss and live birth groups.

A higher hematoma/sac volume ratio and smaller gestational age at SCH diagnosis are associated with a higher rate of early miscarriage. The early miscarriage rate is higher in the patients with SCH diagnosis <8 weeks, with a greater likelihood of large hematomas occurring. Patients with a history of late miscarriages and induced abortions are more likely to have medium or small hematomas. Partial differences in immune status existed between patients with pregnancy loss and those with live birth, warranting attention in clinical diagnosis and treatment.