Journal of Research in Medical Sciences1735-199516920110915Crown-rump length discordance in twins in the first trimester and its correlation with perinatal complications69706970ENZahraShahshahanMaryamHashemiResident, Department of Obstetrics and Gynecology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran. hashemi@yahoo.com2011031720110826BACKGROUND: A difference more than 15-40% in birth weight of twins can predict perinatal complications. As significant difference in twins growth has a very important effect on pregnancy and perinatal complications, this study aimed to evaluate crown-rump length discordance (ΔCRL) in the first trimester of pregnancy and its correlation with perinatal complications. METHODS: A total number of 118 women in the first trimester of twin pregnancy underwent ultrasound examination to measure ΔCRL. Then, at the time of delivery, perinatal complications in twins were recorded and the correlation between ΔCRL and perinatal complications were evaluated. RESULTS: Among 118 studied mothers with twin pregnancy, ΔCRL was normal (< 11%) in 96 cases (81.4%) and high (≥ 11%) in 22 cases (18.6%). Birth weight discordance was normal (< 20%) in 103 cases (87.3%) and above normal (≥ 20%) in 15 cases (12.7%). The results revealed a significant correlation between higher frequency of small for gestational age (SGA) and high ΔCRL (more than 11%) (p = 0.01). CONCLUSIONS: Our study concluded that SGA has a significant relationship with high ΔCRL (> 11%). KEYWORDS: Crown-Rump Length, Discordance, Ultrasound Examination, Twins, Perinatal Complications.