Association Between First-Trimester Intrauterine Hematoma and Twin Pregnancy Outcomes: A Retrospective Cohort Study Wanqing Ji Guangzhou Women and Children's Medical Center Jie Zheng Guangzhou Women and Children's Medical Center Weidong Li Guangzhou Women and Children's Medical Center Fang Guo Guangzhou Women and Children's Medical Center Bo Hou Third Aliated Hospital of Sun Yat-Sen University Ping He ( [email protected] ) Guangzhou Women and Children's Medical Center https://orcid.org/0000-0002-6551-8578 Research article Keywords: intrauterine hematoma, twin gestation, rst trimester, miscarriage, vanishing twin syndrome Posted Date: September 21st, 2020 DOI: https://doi.org/10.21203/rs.3.rs-75567/v1 License: This work is licensed under a Creative Commons Attribution 4.0 International License. Read Full License Version of Record: A version of this preprint was published on January 11th, 2021. See the published version at https://doi.org/10.1186/s12884-020-03528-0. 1 Title page 2 Association between first-trimester intrauterine hematoma and twin pregnancy 3 outcomes: A retrospective cohort study 4 Wanqing Ji1，Ϯ , jie Zheng1，Ϯ, Weidong Li 2，Ϯ, Fang Guo1, , Ping He1，* Bo Hou3，* 5 1Department of Obstetrics, Guangzhou Women and Children’s Medical Center, Guangzhou Medical 6 University, Guangzhou, 510623，China. 7 2Department of Woman and Child Health Information Guangzhou Women and Children’s Medical 8 Center, Guangzhou Medical University, Guangzhou, 510623，China. 9 3Departments of Neurosurgery, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, 10 Guangdong province, 510630, China.E-mail: [email protected] 11 *Correspondence address. Ping He, Guangzhou Women and Children’s Medical Center, Guangzhou 12 Medical University, Guangzhou, Guangdong province, 510623, China.Fax number: 86-20-8717 6790 13 E-mail: [email protected] 14 Bo Hou , Departments of Neurosurgery, The Third Affiliated Hospital, Sun Yat-sen University, 15 Guangzhou, Guangdong province, 510630, China. E-mail: [email protected] 16 Ϯ The authors consider that the first three authors should be regarded as joint First Authors. 17 18 Abstract: 19 Background:In recent years, we have found that first-trimester intrauterine hematoma in twin 20 pregnancy has become increasingly common. The majority of studies on intrauterine hematoma have 21 excluded twin pregnancies, while others did not differentiate between singleton and twin pregnancies. 22 The associations in twin pregnancy are not clear. Therefore, the primary objective of our study was to 23 examine the associations between first-trimester intrauterine hematoma and pregnancy outcomes in 24 twin pregnancy. 25 Material and methods:1020 twin pregnancies in women who underwent a routine examination from 26 January 2014 to December 2018 were enrolled. According to the presence or absence of intrauterine 27 hematoma, we compared the baseline data and pregnancy outcomes between two groups. Multivariable 28 logistic regression analysis was used to adjust for possible confounding factors. 29 Results: A total of 209 patients (21.3%) developed intrauterine hematoma in the first trimester. 30 First-trimester intrauterine hematoma was significantly associated with increased odds of miscarriage 31 (adjusted odds ratio 14.27, 95% CI 8.25-24.70) and the vanishing twin syndrome (adjusted odds ratio 32 3.26, 95% CI 1.11-4.61). However, It did not have increased odds of adverse pregnancy outcomes 33 after 20 Weeks of Gestation .In the final regression model analysis, the associations of hematoma with 34 previous miscarriage history, accepted assisted conception, accompanying vaginal bleeding and 35 miscarriage and vanishing twin syndrome were no longer significant. No association was found 36 between hematoma size or the presence of vaginal bleeding and the risk of pregnancy loss or the 37 vanishing twin syndrome before 20 weeks of gestation (P>0.05). 38 Conclusion: In women with twin pregnancies, the presence of intrauterine hematoma in the first 39 trimester was associated with one or both fetal losses before 20 weeks of gestation. However, 40 chorionicity in twins, the conception method, the intrauterine hematoma size and the presence of 41 vaginal bleeding were not independently associated with pregnancy loss. 42 Keywords: intrauterine hematoma, twin gestation, first trimester, miscarriage, vanishing twin 43 syndrome. 44 Background 45 First-trimester intrauterine hematoma is a common phenomenon observed during routine obstetric 46 ultrasonography. A total of 62.9% of hematomas occur during the first trimester and usually disappear 47 within three months after detection[1]. Evidence suggests that intrauterine hematomas in singleton 48 pregnancies are associated with an increased risk of adverse outcomes[2-4]; however, these results are 49 based on a singleton pregnancies. 50 With the development and application of assisted reproductive techniques, the incidence of twin 51 pregnancy is increasing. It has been reported that assisted reproductive techniques contributed to 16.4% 52 of all multiple-birth infants, and approximately 30.4% of assisted reproductive techniques conceived 53 infants were twins in 2016[5]. In recent years, we have found that first-trimester intrauterine hematoma 54 in twin pregnancy has become increasingly common. Twin pregnancy is associated with a higher 55 incidence of maternal-fetal complications and more adverse pregnancy outcomes, such as early 56 miscarriage, premature birth, preeclampsia, prenatal bleeding, postpartum bleeding, intrauterine growth 57 restriction and stillbirth, than singleton pregnancy[6]. However, it has not been reported whether the 58 effect of intrauterine hematoma in early pregnancy on the outcome in twin pregnancy is the same as 59 that in singleton pregnancy. At present, the majority of studies on intrauterine hematoma have excluded 60 twin pregnancies, while others did not differentiate between singleton and twin pregnancies. The 61 associations in twin pregnancy are not clear. Therefore, the primary objective of our study was to 62 examine the associations between first-trimester intrauterine hematoma and pregnancy outcomes in 63 twin pregnancy. We also assessed the risk factors in women with twin pregnancy. 64 Methods 65 Study population 66 We performed a retrospective analysis of mothers who had two gestational sacs on first trimester 67 ultrasound at Guangzhou Women and Children Medical Center from January 2014 to December 2018. 68 These women underwent ultrasound scans at 5 0/7-13 6/7weeks and underwent routine examination at 69 our medical center. Gestational age was calculated based on last menstrual period or first-trimester 70 ultrasound scan per standard guideline[7]. For the women with assisted reproductive techniques, the 71 gestational week was calculated according to the time of embryo implantation. A twin pregnancy was 72 defined as the presence of two gestational sacs. Viability was confirmed by the presence of fetal 73 cardiac activity on transvaginal ultrasound at 6 to 7 weeks of gestational age.We excluded pregnancies 74 with fetal or placental abnormalities , hematoma found after the operation , or underwent elective 75 termination of pregnancy . The patients were divided into the adverse pregnancy (AP) and normal 76 pregnancy (NP) groups according to the presence or absence of intrauterine hemorrhage. 77 Data collection 78 We reviewed computerized medical records for each woman to obtain demographic ,clinical 79 information and their ultrasound report .Patient demographic data were collected, including maternal 80 age, parity, and abortion history. The gestational age at first detection of intrauterine hematoma, the 81 chorionicity of twins, conception methods and pregnancy results were reviewed in medical records. 82 The volumes of the hematoma were estimated by measuring the maximum transverse, anteroposterior, 83 and longitudinal diameters and multiplying these values by the constant 0.52, as was suggested by 84 Campbel[8]. A correction factor of 0.52 was used to correct for the crescent shape of the hematoma. 85 All measurements were performed with GE Voluson E8 system (GE Healthcare, Milwaukee, WI, USA) 86 by experienced physicians. 87 Maternal and neonatal outcomes were recorded as pregnancy outcomes. The outcomes included 88 spontaneous abortion, vanishing twin syndrome(the heart of one stopped beating before 89 14weeks),preterm delivery at less than 34 weeks of gestation, postpartum hemorrhage, preeclampsia, 90 and low birth weight (selective intrauterine growth restriction or twin-to-twin transfusion syndrome 91 were excluded),Stillbirth ( fetal demise at 20 weeks of gestational age or older) and Fetal distress . 92 Statistical analysis 93 Quantitative characteristics are described as the mean ± standard deviation. A t-test was used for 94 comparison between the AP and NP groups. Qualitative characteristics were described by number 95 (percentage), and the chi-square test was used for comparison between the AP and NP groups.We 96 correlated three groups of intrauterine hematoma size using the Kruskal-Wallis test or chi-square 97 test .The associations between intrauterine hematoma and pregnancy loss were estimated using logistic 98 regression analyses.Initially,unadjusted analyses estimated crude odds ratios and95% confidence 99 intervals (CI) (model 1). Multivariable logistic regression analysis was used to adjust for possible 100 confounding. We carried out data analyses using SAS version 9.4 (SAS Institute Inc.,