Fetal Medicine Foundation charts for fetal growth in twins

Abstract

ObjectivesTo derive reference distributions of estimated fetal weight (EFW) in twins relative to singletons.MethodsGestational age and chorionicity‐specific reference distributions for singleton percentiles and EFW were fitted to data on 4,391 twin pregnancies with two liveborn fetuses from four European centres; there were 3,323 dichorionic (DC) and 1,068 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. The 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 percentiles. Hierarchical models were fitted to singleton z‐scores with autoregressive terms for serial correlations within and between twins; separate models were fitted to DC and MCDA twins.ResultsFetuses from twin pregnancies tended to be smaller than singletons at the earliest gestations; 16 weeks for MCDA and 20 weeks for DC twins. This was followed by a period of catch‐up growth to around 24 weeks. After that, both DC and MCDA twins showed reduced growth. In DC twins, the EFW corresponding to the 50th percentile was on the 50th percentile of singleton pregnancies at 24 weeks, the 43rd percentile at 28 weeks, the 31st percentile at 32 weeks, and the 22nd percentile at 36 weeks. In MCDA twins, the EFW corresponding to the 50th percentile was on the 36th percentile of singleton pregnancies at 24 weeks, the 29th at 28 weeks, the 19th at 32 weeks, and the 12th at 36 weeks.ConclusionsIn DC and, to a greater extent, MCDA twin pregnancies, fetal growth demonstrates a comparatively lower rate than that observed in singleton pregnancies. Furthermore, the divergence in growth trajectories between twin and singleton pregnancies becomes more pronounced as gestational age increases.This article is protected by copyright. All rights reserved.

Incidence of neonatal morbidity in small‐for‐gestational‐age twins based on singleton and twin charts

“…We have reported previously on the Fetal Medicine Foundation fetal and neonatal population weight charts derived from singleton pregnancies 6 , and on charts for monitoring fetal growth in twins 7 . This paper focuses on the question of whether twin fetuses should be classified as small‐for‐gestational age (SGA) using twin‐specific charts or singleton charts.…”

“…The objective of this study was to compare morbidity in SGA singletons and twins when SGA was defined using twin and singleton charts 6,7 . We compared neonatal intensive care (NICU) admission rates and lengths of stay among those classified as SGA using singleton and twin charts for estimated fetal weight (EFW) based on ultrasound assessment at 36 weeks' gestation.…”