Background: In recent years, we have found that first-trimester intrauterine hematoma in twin pregnancy has become increasingly common. The majority of studies on intrauterine hematoma have excluded twin pregnancies, while others did not differentiate between singleton and twin pregnancies. The associations in twin pregnancy are not clear. Therefore, the primary objective of our study was to examine the associations between first-trimester intrauterine hematoma and pregnancy outcomes in twin pregnancy.
Material and methods: 1020 twin pregnancies in women who underwent a routine examination from January 2014 to December 2018 were enrolled. According to the presence or absence of intrauterine hematoma, we compared the baseline data and pregnancy outcomes between two groups. Multivariable logistic regression analysis was used to adjust for possible confounding factors.
Results: A total of 209 patients (21.3%) developed intrauterine hematoma in the first trimester. First-trimester intrauterine hematoma was significantly associated with increased odds of miscarriage (adjusted odds ratio 14.27, 95% CI 8.25-24.70) and the vanishing twin syndrome (adjusted odds ratio 3.26, 95% CI 1.11-4.61). However, It did not have increased odds of adverse pregnancy outcomes after 20 Weeks of Gestation .In the final regression model analysis, the associations of hematoma with previous miscarriage history, accepted assisted conception, accompanying vaginal bleeding and miscarriage and vanishing twin syndrome were no longer significant. No association was found between hematoma size or the presence of vaginal bleeding and the risk of pregnancy loss or the vanishing twin syndrome before 20 weeks of gestation (P>0.05).
Conclusion: In women with twin pregnancies, the presence of intrauterine hematoma in the first trimester was associated with one or both fetal losses before 20 weeks of gestation. However, chorionicity in twins, the conception method, the intrauterine hematoma size and the presence of vaginal bleeding were not independently associated with pregnancy loss.