Risk factors for shoulder dystocia

The risk factors associated with the occurrence of shoulder dystocia were examined in the general obstetrical population of women delivering vaginally. An increasing incidence of shoulder dystocia was found as infant birth weight increased. Although one-third of shoulder dystocia occurred in pregnancies at 42 + weeks, except for those resulting in infants weighing 4500 + g, the vast majority was unaffected by shoulder dystocia. The incidence of shoulder dystocia in nondiabetic gravidas delivering an infant weighing 4000 to 4499 and 4500 + g vaginally was 10.0 and 22.6%, respectively. Within the 4000- to 4499-g group, no labor abnormality was clearly predictive; however, in the heaviest birth weight group, an arrest disorder heralded a shoulder dystocia in 55.0% of cases. Diabetics experienced more shoulder dystocia than nondiabetics. Among them, 31% of vaginally delivered neonates weighing 4000 + g experienced shoulder dystocia. Nevertheless, the risk factors of diabetes and large fetus (4000 + g) could predict 73% of shoulder dystocia among diabetics; large fetus along flagged 52% of shoulder dystocia in nondiabetics. Cesarean section is recommended as the delivery method for diabetic gravidas whose estimated fetal weight is 4000 + g. If others confirm the risk, the authors advise serious consideration of cesarean section for gravidas who are carrying fetuses estimated to be 4500 + g and who experience an abnormal labor.     

Risk factors and neonatal outcomes in shoulder dystocia

BACKGROUND: Shoulder dystocia (SD) is a rare obstetrical complication but linked with a high perinatal morbidity and mortality rate. SD has been associated to a series of maternal and fetal risk factors due to a multifactorial etiology. This study analyzes the incidence of SD, its morbidity and associated risk factors. METHODS: Cases of SD occurred at the St. Gerardo Hospital (Monza) between January 1992 trough December 1997 have been retrospectively reviewed. Obstetrical and feto-neonatal data regarding cases of SD were compared to data regarding all the cephalic vaginal deliveries occurred in the same period in our Center. RESULTS: A total of 14,157 cephalic vaginal deliveries were included in this study, of these 21 infants (0.15%) had SD. A significantly higher incidence of SD cases was found in fetal macrosomia, maternal diabetes, induction of labor by PGE2, use of obstetrical vacuum, length of first stage of labor > 4 hours in multiparas and > 8 hours in nulliparas, and length of second stage > 60 minutes, regardless of parity. A closed association was also observed between SD and birth trauma as brachial plexus injury and humerus fracture. CONCLUSION: The incidence of SD in our population (0.15%) is below the average reported in the literature (0.37-1.1%). The well-known risk factors, whose low positive predictive value can nevertheless modify obstetrical management, are confirmed.     

非巨大儿肩难产发生的高危因素及其临床预测

目的 探讨非巨大儿肩难产发生的高危因素、临床预测及分娩过程中的处理.方法 2009年1月2013年12月间于中国医科大学附属盛京医院经阴道分娩的产妇中发生肩难产11例,同期经阴道分娩产妇7 811例,肩难产发生率为0.14％(11/7 811);其中,巨大儿肩难产1例,非巨大儿肩难产10例(肩难产组).随机抽取每例非巨大儿肩难产病例发生前后1周内经阴道分娩的10例产妇为对照组.分析巨大儿及非巨大儿肩难产的发生趋势及其高危因素,比较两组产妇的宫高、腹围、体质指数(BMI)增长、胎儿双顶径、股骨长、各产程时间、新生儿出生体质量、头围、胸围及Apgar评分.结果 (1)7 811例产妇中共分娩巨大儿213例,巨大儿发生率为2.73％(213/7 811),其中发生巨大儿肩难产1例(0.46％,1/213);非巨大儿肩难产10例(0.13％,10/7 598).(2)2009-2013年的5年间,巨大儿发生率分别为2.32％(24/1 034)、3.61％(42/1 164)、2.60％ (46/1 772)、3.01％(62/2 060)、2.19％(39/1 781),分别比较,差异均无统计学意义(P＞0.05);10例非巨大儿肩难产在5年间的发生比例分别为0.10％(1/1 034)、0.26％(3/1 164)、0.11％(2/1 772)、0.10％(2/2 060)、0.11％(2/1 781),分别比较,差异均无统计学意义(P＞0.05).(3)肩难产组10例产妇中,胎膜早破5例(5/10)、高龄4例(4/10)、经产妇3例(3/10)、妊娠期糖尿病3例(3/10)、第一产程枕后位3例(3/10)、第二产程延长3例(3/10)、常规侧切分娩6例(6/10);对照组产妇中,发生胎膜早破3例(3/10)、高龄1例(1/10)、经产妇2例(2/10)、妊娠期糖尿病3例(3/10)、第二产程时间延长1例(1/10)、常规侧切分娩7例(7/10).(4)两组产妇宫高、BMI、胎儿双顶径、股骨长及第一产程时间分别比较,差异均无统计学意义(P＞0.05).肩难产组及对照组产妇BMI增长[(6.8±3.1)及(4.8±1.4)kg/m2]、第二产程时间[(86±65)及(38±28) min]及腹围[(108±8)及(101±7)cm]分别比较,差异均有统计学意义(P＜0.05).(5)肩难产组及对照组新生儿胸围[(34.0±1.6)及(32.2±1.9) cm]及胸围/头围比值(0.99±0.03及0.97±0.03)比较,差异均有统计学意义(P＜0.05).肩难产组新生儿1分钟Apgar评分[(7.4±2.8)分]明显低于对照组[(10.0±0.0)分],两组比较,差异有统计学意义(P＜0.01).肩难产组新生儿锁骨骨折3例,新生儿发生臂丛神经损伤4例,其余3例无明显副损伤.结论 临床预测非巨大儿肩难产的发生难度较大,通过产前超声测量胎儿头围、胸围及胸围/头围比值可能评估其发生风险;发生非巨大儿肩难产的高危因素为合并胎膜早破、第一产程胎位异常及第二产程延长.     

Determining factors associated with shoulder dystocia: a population-based study

OBJECTIVE: The study was aimed to define obstetric factors associated with shoulder dystocia. METHODS: A population-based study comparing all singleton, vertex, term deliveries with shoulder dystocia with deliveries without shoulder dystocia was performed. Statistical analysis was done using multiple logistic regression analysis. RESULTS: Shoulder dystocia complicated 0.2% (n = 245) of all deliveries included in the study (n = 107965). Independent risk factors for shoulder dystocia in a multivariable analysis were birth-weight > or =4000 g (OR = 24.3; 95% CI 18.5-31.8), vacuum delivery (OR = 5.7, 95% CI 3.4-9.5), diabetes mellitus (OR = 1.7, 95% CI 1.2-2.5) and lack of prenatal care (OR = 1.5, 95% CI 1.1-2.3). A significant linear association was found between birth-weight and shoulder dystocia, using the Mantel-Haenszel procedure. Pregnancies complicated with shoulder dystocia had higher rates of third-degree perineal tears as compared to the comparison group (0.8% versus 0.1%; P < 0.001). Similarly, perinatal mortality was higher among newborns delivered after shoulder dystocia as compared to the comparison group (3.7% versus 0.5%; OR = 7.4, 95% CI 3.5-14.9, P < 0.001). In addition, these newborns had higher rates of Apgar scores lower than 7 at 1 and 5 min as compared to newborns delivered without shoulder dystocia (29.7% versus 3.0%; OR = 13.8, 95% CI 10.3-18.4, P < 0.001 and 2.1% versus 0.3%; OR = 7.2, 95% CI 2.8-18.1, P < 0.001, respectively). Combining risk factors such as large for gestational age, diabetes mellitus and vacuum delivery increased the risk for shoulder dystocia to 6.8% (OR = 32.6, 95% CI 10.1-105.8, P < 0.001). Conclusions: Independent factors associated with shoulder dystocia were birth-weight > or =4000 g, vacuum delivery, diabetes mellitus and lack of prenatal care.     

Critical analysis of risk factors for shoulder dystocia

Objective  

The study was aimed to define trends, risk factors and perinatal outcome associated with shoulder dystocia (SD).     

Maternal and anthropomorphic risk factors for shoulder dystocia

OBJECTIVE: To study maternal and anthropomorphic parameters as potential risk factors for shoulder dystocia. MATERIAL AND METHOD: From a series of 9667 vaginal deliveries between January 1998 and December 2003, a total of 138 cases complicated by shoulder dystocia were retrospectively identified and compared with a control group of 138 uncomplicated vaginal deliveries. In addition to maternal age, parity, diabetes, body mass index (BMI), and ethnicity, anthropometric factors including maternal height-to-infant weight ratio, characteristics of labor, management techniques, and outcome were evaluated as possible risk factors for shoulder dystocia. RESULTS: The overall incidence of shoulder dystocia in this retrospective series of vaginal deliveries was 1.4%. In univariate analysis, maternal obesity (OR; 95% CI: 3.6; 2.1-6.3), diabetes (OR: 19.4; 2.5-145.7), parity greater than 2 (OR: 2.5; 1.4-4.4), maternal height-to-infant weight ratio (OR: 1.02; 1.01-1.04; P < 0.001), and infant weight-to-maternal BMI ratio (OR: 1.02; 1.01-1.03; P < 0.001) were predictive of shoulder dystocia. In multiple regression analysis, obesity and multiparity were the most significant maternal risk factors for shoulder dystocia. The only anthropometric factors associated with shoulder dystocia in multiple regression analysis were maternal height <1.55 m (OR: 6.6; 1.3-34.9) and maternal height-to-infant weight ratio (OR: 1.02; 1.01-1.05). CONCLUSION: Shoulder dystocia may be anticipated in cases involving short women and discrepancy between maternal height or weight and infant weight.     

肩难产综合预防措施的荟萃分析

目的 探讨肩难产的综合预防措施.方法 计算机检索2014年5月以前的PubMed数据库、美国EBSCO数据库、荷兰医学文摘数据库、Cochrane图书馆数据库,以“shoulder dystocia and prevention”为主题词检索英文文献.对检索到的文献进行质量评价,文献研究类型仅限于随机对照临床试验(RCT)研究;研究对象为经阴道分娩产妇,干预措施包括孕期管理、预防性引产、预防性剖宫产术,预防性肩难产处理.纳入的文献采用RevMan 5.1软件进行荟萃分析,以肩难产发生率作为终点指标.结果 共有16篇英文文献纳入荟萃分析,发表时间为1993-2009年.(1)对妊娠期糖尿病(GDM)孕妇的孕期干预:有2篇文献比较了GDM孕妇的孕期干预(干预组)与不干预(不干预组)对肩难产发生率的影响,结果显示,干预组肩难产发生率显著低于不干预组(OR=0.40,95％ CI为0.21～0.75,P=0.004).(2)对GDM孕妇的孕期严格干预:5篇文献比较了GDM孕妇的孕期严格干预(饮食控制+胰岛素应用;严格干预组)与不严格干预(单纯饮食控制等;不严格干预组)对肩难产发生率的影响,结果显示,严格干预组肩难产发生率显著低于不严格干预组(OR=0.29,95％CI为0.11～ 0.73,P=0.009).(3)非糖尿病孕妇可疑巨大儿者引产:有4篇文献比较了非糖尿病孕妇可疑巨大儿者提前引产(提前引产组)对肩难产发生的影响,结果显示,提前引产组肩难产发生率与对照组比较,差异无统计学意义(OR=0.85,95％CI为0.41～ 1.75,P=0.660).(4)GDM孕妇引产:有2篇文献比较了GDM孕妇提前引产(孕38～ 39周;提前引产组)对肩难产发生的影响,结果显示,提前引产组肩难产发生率与对照组比较,差异有统计学意义(OR=0.18,95％CI为0.03～ 0.97,P=0.050);只与对照组中孕40周以后分娩者比较,提前引产组肩难产发生率显著低于对照组(OR=0.13,95％ CI为0.02～ 0.75,P=0.020).(5)GDM孕妇可疑巨大儿者提前终止妊娠:仅有1篇文献比较了GDM孕妇中可疑巨大儿者提前终止妊娠(提前终止妊娠)对肩难产发生率的影响,结果显示,提前终止妊娠组的肩难产发生率与对照组比较,差异有统计学意义(OR=0.34,95％CI为0.12～ 0.99,P=0.050).(6)产时预防性干预(产时干预组)对肩难产发生率的影响:有2篇文献比较了产时胎头娩出后行预防性干预对肩难产发生率的影响,结果显示,产时干预组肩难产发生率与对照组比较,差异无统计学意义(OR=0.44,95％CI为0.16～ 1.18,P=0.100).结论 对有肩难产高危因素的孕妇适当进行临床措施的干预,可明显降低肩难产的发生率.     

Complications of shoulder dystocia

Complications of shoulder dystocia are divided into fetal and maternal. Fetal brachial plexus injury (BPI) is the most common fetal complication occurring in 4–40% of cases. BPI has also been reported in abdominal deliveries and in deliveries not complicated by shoulder dystocia. Fractures of the fetal humerus and clavicle occur in about 10.6% of cases of shoulder dystocia and usually heal with no sequel. Hypoxic ischemic brain injury is reported in 0.5–23% of cases of shoulder dystocia. The risk correlates with the duration of head-to-body delivery and is especially increased when the duration is >5 min. Fetal death is rare and is reported in 0.4% of cases. Maternal complications of shoulder dystocia include post-partum hemorrhage, vaginal lacerations, anal tears, and uterine rupture. The psychological stress impact of shoulder dystocia is under-recognized and deserves counseling prior to home discharge.