Twin and singleton growth patterns compared using US.

Sonography has been used widely in the evaluation of singleton fetal growth. Twin gestations, however, have received less careful attention. In a statistical study of 103 twin pregnancies, the growth patterns of twin biparietal diameter (BPD), fetal femur length (FFL), and abdominal circumference (AC) were compared with those of singletons. The results of the study revealed a decrease in twin BPD growth after 31 to 32 weeks of gestation relative to singletons. Twin AC growth rate decreases after 32-33 weeks of gestation relative to singletons, but the twin FFL growth pattern does not deviate from that of singletons throughout gestation. Because of the significant difference in growth patterns of BPD and AC between twins and singletons in our population, new growth charts for twin BPD and AC are proposed.