Investigation of the Association of Abdominal Circumference Discord-ance and Estimated Fetal Weight Discordance in Twins with Birth Weight Discordance.

Background: Twin pregnancy is associated with a high risk of mortality and morbidity. It is necessary to estimate the weight difference of the fetuses with a reliable method to prevent possible complications. This study was conducted to compare the association between the Estimated fetal weight (EFW) discord-ance and the Abdominal Circumference (AC) discordance with birth weight in twins.

Methods: This was a descriptive-analytical and retrospective study. The statistical population was all twin pregnant mothers referred to Imam Khomeini Hospital in Ahvaz from 2017 to 2019. The sample size was determined with a census (540 people). Based on AC , the size of head circumference (HC), femur length (FL), and the Biparietal Diameter (BPD), EFW was calculated. Then the EFW Dis-cordance and AC Discordance were calculated and compared with the birth weight. Data were analyzed using SPSS18. Unpaired, Two-Tailed T-test and Pearson correlation test were used.

Results: The results showed that the mean discordance of fetal weight in twin pregnancies in the EFW method was 9.25%, in the AC method was 9.89% and finally, at birth, was 10.72%. The correla-tion of the weight difference between the two embryos in the AC method with the time of birth (r = 0.922 and P < 0.001) was higher than in the EFW method with the time of birth (r = 0.69 and P < 0.001) and finally, it was found that in detecting the discordance more than 20% and 25%, AC diagnostic power was good, but EFW was moderate.

Conclusion: Therefore, to evaluate the weight and weight difference in twin embryos, the AC method has the appropriate accuracy and compatibility. Another major prospective study to evaluate the diagnostic performance of AC and EFW mismatch based on gestational age at scan, incision point, and maternal and placental characteristics to determine true ultrasound diagnostic accuracy in predict-ing growth mismatch in twin pregnancy and optimal post-case management option is needed.