4.1 Main findings
Based on a large data set of ultrasonographic biometric measurements, we are the first to develop fetal ultrasound biometric standards, including EFW, BPD, HC, AC, FL and HL, among Chinese uncomplicated twin pregnancies. The major strength of this study lies in taking both chorionicity and mode of conception into account, and the findings showed that SC-DCDA twins had faster growth rate than SC-MCDA twins, while slower than ART-DCDA twins. When making comparison with data from singletons, all of the three shows slower growth pattern, however, the contrasts were mainly observed during the third trimester. The data enriched our understanding on the twin-specific fetal growth trajectories, and the standards established in this study have potential to promote more accurate assessment of intrauterine growth trajectory for Chinese twins.