探讨死胎发生的相关因素变迁，为评价及优化死胎防控措施提供依据。

选择2008—2021年于四川大学华西第二医院(中国区域围产医学中心之一)住院终止妊娠的胎儿总计为152 490中的652例死胎(均为单胎妊娠)为研究对象，并纳入全阶段组。采取回顾性分析法，将652例死胎按照发生年份，分别纳入前阶段组(n＝447，2008—2014年在本院住院终止妊娠的胎儿总数为55 508例)与后阶段组(n＝205，2015—2021年在本院住院终止妊娠的胎儿总数为96 982例)。本研究遵循的程序符合2013年修订的《世界医学协会赫尔辛基宣言》。

2008—2021年，本研究死胎平均发生率为0.428%，其中前阶段组为0.805%,后阶段组为0.211%。后阶段组导致死胎相关因素占比由高到低依次为母体因素(61.46%)、脐带因素(20.98%)、胎盘因素(20.49%)、胎儿因素(15.60%)、不明原因(8.29%)。①母体因素：死胎相关母体因素主要为妊娠合并心血管疾病、糖尿病、妊娠期肝内胆汁淤积症、甲状腺功能异常；其导致的死胎胎龄为31~34⁺⁶周；后阶段组母体妊娠合并甲状腺功能异常相关的死胎比例，较前阶段组显著升高，差异有统计学意义(χ²＝28.83，P<0.001)。②脐带因素：后阶段死胎相关脐带因素从高到低依次为脐带扭转(17.56%)、缠绕(1.95%)、脱垂(0.49%)；其发生的死胎胎龄为32~33⁺⁶周；后阶段组脐带扭转占比，较前阶段组显著升高，差异有统计学意义(χ²＝8.62，P＝0.003)，而脐带脱垂占比，则较前阶段组显著下降，差异亦有统计学意义(χ²＝8.46，P＝0.004))。③胎盘因素：后阶段死胎相关胎盘因素由高到低依次为前置胎盘(7.80%)、胎盘早剥(4.39%)；其导致的死胎胎龄为31~33⁺⁶周；后阶段组死胎前置胎盘占比，较前阶段组显著上升，差异有统计学意义(χ²＝4.20，P＝0.041)。④胎儿因素：以胎儿发育异常(11.20%)多见，其导致的死胎胎龄为31~33⁺⁶周。⑤不明原因：其导致的死胎胎龄为29~33⁺⁶周；后阶段组死胎不明因素占比，较前阶段组显著下降，差异有统计学意义(χ²＝5.94，P＝0.015)。

加强对死胎病因疾病谱、尤其是重点疾病的管理和母胎保健，防控其导致死胎相关因素引起的病理进展，监测胎儿宫内生长、发育状态，尤其在胎儿发育的关键风险时段，及时发现胎儿宫内不良状态，健全高危妊娠转诊及宫内转运绿色通道，适时积极终止妊娠，这些措施对降低我国死胎发生率，均具有至关重要作用。

To explore the changes in risk factors related to stillbirth, and provide basis for evaluating and optimizing the prevention and control measures of stillbirth.

A total of 652 stillborn fetuses (all from singleton pregnancies) were selected in this study from 2008 to 2021 at West China Second University Hospital of Sichuan University, one of the regional centers for perinatal medicine in China. A retrospective analysis was conducted, and the 652 cases of stillbirth were divided into two groups based on the year of occurrence: the early-stage group (n=447, total number of in-patient deliveries of fetuses in our hospitals from 2008-2014 was 55 508) and the late-stage group (n=205, total number of inpatient deliveries of fetuses in our hospitals from 2015-2021 is 96 982). The procedures followed in this study were in accordance with the revised 2013 Declaration of Helsinki by the World Medical Association.

From 2008 to 2021, the average incidence rate of stillbirths in this study was 0.428%, with 0.805% in the early-stage group and 0.211% in the late-stage group. The late-stage group′s proportion of factors contributing to stillbirths, from highest to lowest, was maternal factors (61.46%), umbilical cord factors (20.98%), placental factors (20.49%), fetal factors (15.61%), and unknown causes (8.29%). ① Maternal factors: The main maternal factors associated with stillbirths were maternal cardiovascular diseases, diabetes, intrahepatic cholestasis of pregnancy, and thyroid diseases. The gestational week of stillbirths was mainly between 31 and 34^{+ 6} weeks. The proportion of stillbirths associated with thyroid disease in the late-stage pregnancies significantly increased compared to the early-stage group (χ²=28.83, P<0.001). ② Umbilical cord factors: The late-stage group′s umbilical cord factors contributing to stillbirths, from highest to lowest, were cord torsion (17.56%), cord entanglement (1.95%), and cord prolapse (0.49%). The gestational week of stillbirths was mainly between 32 and 33^{+ 6} weeks. The proportion of cord torsion significantly increased in the late-stage group compared to the early-stage group (χ²=8.62, P=0.003), while the proportion of cord prolapse significantly decreased (χ²=8.46, P=0.004). ③ Placental factors: The late-stage group′s placental factors associated with stillbirths, from highest to lowest, were placenta previa (7.80%) and placental abruption (4.39%). The gestational week of stillbirths was mainly between 31 and 33^{+ 6} weeks. The proportion of stillbirths associated with placenta previa significantly increased in the late-stage group compared to the early-stage group (χ²=4.20, P=0.041). ④ Fetal factors: Abnormal fetal development (11.20%) was the most common fetal factor. The gestational age of stillbirths was mainly between 31 and 33^{+ 6} weeks. ⑤ Unknown causes: The proportion of stillbirths with unknown causes significantly decreased in the late-stage group compared to the early-stage group (χ²=5.94, P=0.015), and the occurrence of stillbirths was mainly between 29 and 33^{+ 6} weeks of gestation.

Strengthening the management of etiological spectrum diseases associated with stillbirths, especially focusing on key diseases, and enhancing maternal and fetal healthcare interventions are crucial in preventing and controlling pathological progression caused by relevant factors leading to fetal demise. Monitoring fetal intrauterine growth and intrauterine conditions, particularly during critical risk periods, enables timely detection of adverse intrauterine conditions in the fetus. Establishing efficient referral systems and green channels for intrauterine transportation of high-risk pregnancies, along with timely and proactive termination of pregnancies, play a vital role in reducing the stillbirth rate in China. These measures are of paramount importance.