Luke B
Department of Obstetrics and Gynecology, Rush Medical College, Rush-Presbyterian-St. Luke's Medical Center, Chicago, Illinois.
Obstet Gynecol. 1994 Jul;84(1):101-6.
To evaluate changes in the incidence and proportion of live births by plurality in the United States between 1960 and 1990, and to compare the distribution of singleton, twin, and triplet and higher-order births (triplet+) by maternal and infant characteristics for 1973 and 1990.
Vital statistics data were used to conduct a population-based analysis of all live births from 1960-1990 and to compare changes in the incidence and outcomes of live births between 1973 and 1990 by maternal and infant characteristics.
Between 1960 and 1973, the number of twin births paralleled that of singletons, whereas the number of triplet+ births remained fairly constant. Between 1973 and 1990, twin births increased at twice the rate of singletons (65 versus 32%), and triplet+ births increased at seven times the rate of singletons (221 versus 32%). The resulting frequencies of occurrence changed from one in 55 to one in 43 births for twins and from one in 3323 to one in 1341 for triplet+ births. In 1990, preterm births accounted for 9.7% of singleton births, compared to 47.9% of twin births and 87.8% of triplet+ births. Because of the greater frequency of twin and triplet+ births in 1990, the observed number of very low and low birth weight infants was 24.2% greater among twin births and 142.3% greater among triplet+ births than would be expected if the 1973 ratios to singleton births had remained constant.
The rise in multiple births, with the associated greater risks of prematurity and low birth weight, is of national importance. Comprehensive and aggressive prenatal care to assure the best outcomes should be the goal for clinicians caring for these women.
评估1960年至1990年间美国不同胎次活产的发生率及比例变化，并比较1973年和1990年单胎、双胎、三胎及多胎（三胎及以上）分娩按母婴特征的分布情况。
利用生命统计数据对1960 - 1990年所有活产进行基于人群的分析，并比较1973年和1990年间活产的发生率及结局按母婴特征的变化。
1960年至1973年间，双胎分娩数量与单胎分娩数量平行增长，而三胎及以上分娩数量保持相对稳定。1973年至1990年间，双胎分娩的增长率是单胎分娩的两倍（65%对32%），三胎及以上分娩的增长率是单胎分娩的七倍（221%对32%）。由此产生的双胎分娩发生频率从每55例出生中有1例变为每43例出生中有1例，三胎及以上分娩发生频率从每3323例出生中有1例变为每1341例出生中有1例。1990年，早产在单胎分娩中占9.7%，在双胎分娩中占47.9%，在三胎及以上分娩中占87.8%。由于1990年双胎及三胎及以上分娩频率更高，如果1973年与单胎分娩的比例保持不变，那么观察到的极低和低出生体重婴儿数量在双胎分娩中比预期多24.2%，在三胎及以上分娩中比预期多142.3%。
多胎分娩增加，以及随之而来的早产和低出生体重风险增加，具有全国性重要意义。为确保最佳结局而提供全面且积极的产前护理应是照顾这些孕妇的临床医生的目标。
