NEW BIRTH-WEIGHT NOMOGRAMS FOR TWIN GESTATION ON THE BASIS OF ACCURATE GESTATIONAL-AGE

OBJECTIVE: Our purpose was to establish new nomograms for the birth we ight of twins on the basis of accurate methods to validate gestational age. STUDY DESIGN: The medical records of 1632 consecutive twin gesta tions delivered between 1984 and 1996 were reviewed. Only pregnancies induced by ovulation induction techniques or that were measured ultras onographically for crown-rump length during the first trimester were i ncluded. Excluded were those whose fetuses (one or both) were stillbor n, or if the mother smoked, had a significant chronic illness, or was prescribed any regular medications. The study comprised 520 twin pregn ancies at 28 to 41 gestational weeks at delivery. RESULTS: The median and 10th and 90th percentile birth weight curves were calculated for t he studied twins and plotted against previously reported singleton nom ograms. Fetuses of twin pregnancies were found to be growth restricted in comparison with previously reported singletons throughout the thir d trimester. This trend became more evident after the thirty-fourth to thirty-sixth weeks.CONCLUSIONS: We recommend these novel birth weight nomograms for clinical ise in the management of twin pregnancies.