New birthweight normograms for twin gestation based on highly accurate gestational age

OBJECTIVE: To establish new normograms for twins birthweight based on highly accurate methods to validate gestational age. STUDY DESIGN: Medical records of 1,632 consecutive twin gestations delivered between 1984 and 1996 were reviewed- We included only pregnancies that were induced by ovulation induction techniques or in which ultrasonographic measurements of crown-rump-length during the 1st trimester was done. We excluded those who had one or both fetuses stillborn, or if the mother had any significant chronic illness, prescribed on anyregular medications, or smoked. A total of 520 twin pregnancies at 28-41 gestational weeks at delivery were included in the study. RESULTS: The median, 10th and 90th percentile birthweight curves were calculated for the studied twins (figure), and plotted against previously reported singleton normograms (Hadlock, 3984). CONCLUSIONS: We recommend these novel birthweight normograms for clinical use in the management of twin pregnancies. Fetuses of twin pregnancies were found to be growth-restricted in comparison to singleton, throughout the third trimester. This trend is facilitated after the 36th week.