Aurora Health Care and Center for Urban Population Health, Milwaukee, WI, USA.
Am J Obstet Gynecol. 2010 Oct;203(4):305-15. doi: 10.1016/j.ajog.2010.04.031. Epub 2010 Aug 21.
The rate of twin pregnancies in the United States has stabilized at 32 per 1000 births in 2006. Aside from determining chorionicity, first-trimester screening and second-trimester ultrasound scanning should ascertain whether there are structural or chromosomal abnormalities. Compared with singleton births, genetic amniocentesis-related loss at <24 weeks of gestation for twin births is higher (0.9% vs 2.9%, respectively). Selective termination for an anomalous fetus is an option, although the pregnancy loss rate is 7% at experienced centers. For singleton and twin births for African American and white women, approximately 50% of preterm births are indicated; approximately one-third of these births are spontaneous, and 10% of the births occur after preterm premature rupture of membranes. From 1989-2000, the rate of preterm twin births increased, for African American and white women alike, although the perinatal mortality rate has actually decreased. As with singleton births, tocolytics should be used judiciously and only for a limited time (<48 hours) in twin births. Administration of antenatal corticosteroids is an evidence-based recommendation.
2006 年，美国的双胞胎妊娠率稳定在每 1000 例活产中 32 例。除了确定绒毛膜性外，早孕期筛查和中孕期超声扫描应确定是否存在结构或染色体异常。与单胎妊娠相比，<24 孕周行遗传羊膜腔穿刺术的相关丢失率在双胎妊娠中更高（分别为 0.9%和 2.9%）。对于异常胎儿，选择性终止妊娠是一种选择，尽管在有经验的中心，妊娠丢失率为 7%。对于非裔美国人和白人妇女的单胎和双胎妊娠，约有 50%的早产是指征性的；其中约三分之一是自发性的，10%的分娩发生在早产胎膜早破之后。从 1989 年至 2000 年，非裔美国人和白人妇女的双胎早产率均有所上升，尽管围产儿死亡率实际上有所下降。与单胎分娩一样，双胎妊娠也应谨慎使用宫缩抑制剂，且时间有限（<48 小时）。产前使用皮质类固醇是一项基于证据的推荐。
