目的:推导出双胞胎相对于单胎的估计胎儿体重(EFW)的参考分布。
方法:将单胎百分位数和EFW的妊娠年龄和绒毛膜特异性参考分布与来自四个欧洲中心的4,391例双胎妊娠和两个活产胎儿的数据拟合;有3,323例双胎(DC)和1,068例单绒毛膜双胎(MCDA)妊娠。妊娠年龄是使用在怀孕的头三个月期间获得的两个冠-臀部长度测量值中的较大者得出的。EFW是从头围的超声测量中获得的,腹围,和股骨长度使用Hadlock公式。使用胎儿医学基金会人口体重图获得单胎百分位数。将分层模型拟合到单例z分数,并带有自回归项,用于双胞胎内部和之间的序列相关性;将单独的模型拟合到DC和MCDA双胞胎。
结果:双胎妊娠的胎儿在最早妊娠时往往比单胎小;MCDA为16周,DC双胞胎为20周。随后是大约24周的追赶增长期。之后,DC和MCDA双胞胎均显示生长减少.在DC双胞胎中,对应于第50百分位数的EFW是24周时单胎妊娠的第50百分位数,第43百分位数在28周,32周时的第31百分位数,36周时的第22百分位数。在MCDA双胞胎中,对应于第50百分位数的EFW是24周时单胎妊娠的第36百分位数,29日28周,第32周的第19天,和第12周在36周。
结论:在DC和,在更大程度上,MCDA双胎妊娠,与单胎妊娠相比,胎儿的生长速度相对较低。此外,随着胎龄的增加,双胎妊娠和单胎妊娠之间的生长轨迹差异变得更加明显。本文受版权保护。保留所有权利。
To derive reference distributions of estimated fetal weight (EFW) in twins relative to singletons.
Gestational-age- and chorionicity-specific reference distributions for singleton percentiles and EFW were fitted to data on 4391 twin pregnancies with two liveborn fetuses from four European centers, including 3323 dichorionic (DC) and 1068 monochorionic diamniotic (MCDA) twin pregnancies. Gestational age was derived using the larger of the two crown-rump length measurements obtained during the first trimester of pregnancy. EFW was obtained from ultrasound measurements of head circumference, abdominal circumference and femur length using the Hadlock formula. Singleton percentiles were obtained using the Fetal Medicine Foundation population weight charts for singleton pregnancies. Hierarchical models were fitted to singleton Z-scores with autoregressive terms for serial correlations within the same fetus and between twins from the same pregnancy. Separate models were fitted for DC and MCDA twins.
Fetuses from twin pregnancies tended to be smaller than singletons at the earliest gestational ages (16 weeks for MCDA and 20 weeks for DC twins). This was followed by a period of catch-up growth until around 24 weeks. After that, both DC and MCDA twins showed reduced growth. In DC twins, the EFW corresponding to the 50th percentile was at the 50th percentile of singleton pregnancies at 23 weeks, the 43rd percentile at 28 weeks, the 32nd percentile at 32 weeks and the 22nd percentile at 36 weeks. In MCDA twins, the EFW corresponding to the 50th percentile was at the 36th percentile of singleton pregnancies at 24 weeks, the 29th percentile at 28 weeks, the 19th percentile at 32 weeks and the 12th percentile at 36 weeks.
In DC and, to a greater extent, MCDA twin pregnancies, fetal growth is reduced compared with that observed in singleton pregnancies. Furthermore, after 24 weeks, the divergence in growth trajectories between twin and singleton pregnancies becomes more pronounced as gestational age increases. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.