目的：分析24h产后出血量≥1000ml患者需要输血的危险因素，并针对相关危险因素为产前保健提出预防措施。

方法：回顾性分析2017年1月1日至2019年12月31日在南京鼓楼医院分娩且产后24h内出血量≥1000ml孕产妇的临床资料，根据患者是否在分娩时或产后住院期间接受红细胞输注，分为输血组和非输血组。首先对可能导致严重产后出血患者接受输血的因素进行单因素分析，然后对有统计学差异的各因素进行多因素二元Logistic回归分析。

结果：2017年1月1日至2019年12月31日共有22049例孕妇在南京鼓楼医院分娩，24h产后出血量≥1000ml 的产妇共814例，严重产后出血患病率3.7%，剔除17例相关参数不全的患者，共纳入797例分析。24h平均产后出血量为（1497±747）ml ，其中非输血组582例，输血组215例，输血率27.0%（215/797）。产前贫血者144例，占18.1%(144/797)。本研究中严重产后出血的主要原因为子宫收缩乏力，占62.2%（497/797），继之依次为胎盘因素23.1%（184/797）、软产道裂伤9.0%（72/797）、凝血功能异常占5.7%（45/797）。两组单因素分析发现输血组与非输血组的高龄孕妇比例、孕产次、产前一周内体质指数、分娩方式、前置胎盘、胎盘植入、胎盘早剥、瘢痕子宫、产前贫血、妊娠期糖尿病、子宫发育异常的发生率以及24h产后出血量均有显著差异（P<0.05）。根据Logistic回归分析显示， 24h产后出血总量需要输血的危险系数最大，其次为前置胎盘，而产前贫血紧随其后。与血红蛋白正常的严重产后出血患者相比，贫血患者需要输血的风险增加1.80倍。当出血量在1000 ~ <1500ml时，贫血者输血率为17.8%，而非贫血者输血率不及贫血者的一半（17.8% vs 8.1%，c²=8.011，P＜0.05）。当出血量在1500 ~ <2000ml时，贫血者输血率超过75%，远高于非贫血者。当24h出血量≥2200ml时，无论贫血与否，均需输血。8例发生了失血性休克，19例需入住ICU，无孕产妇死亡。

结论：24h产后出血量、前置胎盘、产前贫血是严重产后出血患者需要输血的危险因素。准确评估产时及产后出血量，快速有效处理产后出血，产前积极纠正贫血，适当增加孕期体重，提高患者对出血的耐受性是减少严重产后出血输血需求的重要措施。对前置胎盘，尤其是伴胎盘植入的凶险性前置胎盘患者，产前准确评估医院的救治能力，如有困难应及时转诊患者至有条件的医院分娩。

Objective: To evaluate the risk factors for blood transfusion in postpartum hemorrhage patients with blood loss ≥1000ml within 24 hours.

Methods: A retrospective case control study was performed on the clinical data of the pregnant women who gave birth in Nanjing Drum Tower hospital from January 1, 2017 to December 31, 2019, and suffered from postpartum blood loss ≥ 1000ml within 24 hours after delivery. According to whether the patients received RBC infusion during delivery or during postpartum hospitalization, they were divided into blood transfusion group and non-blood transfusion group. We first compared the individual factors that may cause the patient to receive blood transfusion, and then perform a multivariate binary Logistic regression analysis on the statistically different factors.

Results：From January 1, 2017 to December 31, 2019, a total of 22049 pregnant women delivered in Nanjing Drum Tower hospital, and 814 patients with blood loss ≥1000ml within 24 hours after delivery. The prevalence of severe postpartum hemorrhage was 3.7%. Seventeen patients were excluded due to incomplete data, and 797 cases were included in this study. The average 24h-blood loss after delivery of the patients was (1497±747) ml. There were 215 patients receiving blood transfusion and 582 patients in the non-transfusion group, and the rate of the blood transfusion was 27.0%.There were 144 cases of prenatal anemia, accounting for 18.1%.

Uterine atony was the main cause of severe postpartum hemorrhage ,accounting for 62.2% (497/797), followed by placental factors 23.1% (184/797), soft birth canal laceration 9.0% (72/797) and abnormal coagulation function 5.7% (45/797).Single factor analysis found that there are 13 indicators with statistical differences (P<0.05). Logistic regression analysis showed that the highest risk factor of blood transfusion was the total amount of postpartum hemorrhage within 24 hours. The second was placenta previa. Prenatal anemia was also one of the risk factors.Compared with those with normal level of hemoglobin, those with prenatal anemia had a 1.80 times higher risk of needing blood transfusion. The risk of blood transfusion was reduced in patients with relatively higher prenatal body mass index.

Conclusions: 24h-postpartum hemorrhage volume, placenta previa, and prenatal anemia are risk factors for blood transfusion in patients with severe postpartum hemorrhage. Rapidly and effectively arresting hemorrhage, actively correct anemia before childbirth, appropriately increase weight during pregnancy are important for reducing the need of blood transfusion in severe postpartum hemorrhage patients.