Onah H E
Department of Obstetrics and Gynaecology, University of Nigeria Teaching Hospital, Enugu, Nigeria.
Int J Gynaecol Obstet. 2003 Mar;80(3):255-61. doi: 10.1016/s0020-7292(02)00381-8.
(1) To determine the distribution of singleton and twin births according to gestational age in a Nigerian obstetric population; and (2) to compare their perinatal outcomes according to gestational age.
A 10-year retrospective comparative study of twin and singleton births at a tertiary care center in Enugu, Nigeria. The variables analyzed were: the proportion of deliveries occurring at each gestational age, the gestational age-specific rates for stillbirths, cesarean section, babies with 1-min Apgar scores less than 4 and those whose birthweights were below the 10th percentile for gestational age. The trends in these rates were determined by finding the best fitting polynomial regression curve for each variable. Tests of statistical significance for trends in proportions were carried out by means of the chi(2)-test at the 95% confidence level.
Of the 496 twin births, 3.6% compared with 17.3% of the 496 singleton births went beyond 40 weeks' gestation while 1.2% of the twin and 4.4% of the singleton deliveries occurred at 42 weeks' gestation or beyond. For twins as well as singletons, there was a consistent and significant decline in the stillbirth rate and the proportion of babies with 1-min Apgar scores less than 4 up to 42 weeks (P=0.0000). Among the twins, the proportion of babies with birthweights below the 10th percentile (i.e. those with impaired growth) significantly rose from 28 weeks and above (P=0.0000) while among the singletons, a declining trend with gestational age was observed (P=0.0003). However, among the twins with impaired growth, the stillbirth rate neither differed between the first and second twins at each gestational age nor did it increase with gestational age in both the first and second twins. While the cesarean section rate for singletons remained almost stable at approximately 13%, there was a significant rise in the cesarean section rate with gestational age among the twin births.
There were 1.2% of twin deliveries compared with 4.4% of singleton deliveries which occurred at 42 weeks' gestation or beyond. In the Nigerian population studied, the perinatal outcomes in twins did not differ from those of singletons up to 42 weeks' gestation suggesting that the 42-week cut-off for prolonged pregnancy applies equally well to twins as to singletons.
（1）确定尼日利亚产科人群中单胎和双胎分娩按孕周的分布情况；（2）比较它们按孕周的围产期结局。
对尼日利亚埃努古一家三级医疗中心的双胎和单胎分娩进行为期10年的回顾性比较研究。分析的变量包括：每个孕周分娩的比例、死产的孕周特异性率、剖宫产率、1分钟阿氏评分低于4分的婴儿比例以及出生体重低于孕周第10百分位数的婴儿比例。通过为每个变量找到最佳拟合多项式回归曲线来确定这些率的趋势。采用卡方检验在95%置信水平下对比例趋势进行统计学显著性检验。
在496例双胎分娩中，3.6%的双胎与496例单胎分娩中17.3%的单胎超过40周妊娠，而1.2%的双胎和4.4%的单胎分娩发生在42周及以后。对于双胎和单胎，直至42周，死产率以及1分钟阿氏评分低于4分的婴儿比例均持续且显著下降（P = 0.0000）。在双胎中，出生体重低于第10百分位数（即生长受限）的婴儿比例从28周及以上显著上升（P = 0.0000），而在单胎中，观察到随孕周呈下降趋势（P = 0.0003）。然而，在生长受限的双胎中，每个孕周第一和第二胎儿的死产率既无差异，第一和第二胎儿的死产率也不随孕周增加。单胎剖宫产率几乎稳定在约13%，而双胎分娩的剖宫产率随孕周显著上升。
42周及以后分娩的双胎占1.2%，单胎占4.4%。在本研究的尼日利亚人群中，直至42周，双胎的围产期结局与单胎无异，这表明过期妊娠的42周界限对双胎和单胎同样适用。
