Fetal Growth Chart in Twins Consistent with The FMF Growth Curve:Prospective Multicenter Study

Objectives: Different retrospective growth charts for twin pregnancies debates whether twin growth is similar to singletons. Recently, the fetal medicine foundation (FMF) published a retrospective fetal growth chart that indicated similar growth charts for twins and singleton if only term delivery of both twins without major malformation are included. A national Denish growth chart confirmed these finding. We constructed prospective growth chart of estimated fetal weight (EFW) throughout pregnancy of monochorionic diamniotic (MCDA) and dichorionic (DC) twins using a multi-center, multi-national cohort. Study Design: Pregnancies with two live fetuses at 11-13 wks’ gestation were enrolled. Gestational age was determined from crown-rump length of the larger twin in the first trimester. EFW charts were made from fetal growth at 11-13, 20-22, 24-26, 28-30, 32-34, and 36-37 wks’ gestation using Hadlock-4 formula made of biparietal diameter, head and abdominal circumference, and femur length. Chorionicity specific charts were built for 376 DC and 158 MCDA live twins who were born at term, without malformations. Centers included were from Montreal, Canada, Bonn and Tubingen, Germany, Barcelona, Spain, Rome, Italy, and Zerifin, Israel. ANOVA was used to compare ethnic and centers charts and functional fit to were compared our charts to retrospective EFW charts of the FMF. Results: Growth was slower in MCDA compared with DC twins starting from 21st wks’ gestation and increased with advancing gestation. Our charts were similar but marginally slower than the FMF ones. Smaller EFW were in Barcelona and Rome compared to the larger in Bonn and Tubingen, and fetuses of white women were larger than those of other ethnicities Conclusions: We developed a prospective growth chart for pregnancies with two live DC and MCDA twins born at term without malformations that are consistent with those of the FMF, with small differences between countries and ethnicities.