Berger G S, Edelman D A, Kerenyi T D
Am J Obstet Gynecol. 1975 May 1;122(1):9-12. doi: 10.1016/0002-9378(75)90607-9.
This study examines the relationships between fetal size (biparietal diameter and crown-rump length) and gestational age among subjects aborted by hypertonic saline in the second trimester of pregnancy. With a confidence of 90 per cent, biparietal diameter can be used to predict gestational age within plus or minus 2 weeks, and crown-rump length can be used to predict gestational age within plus or minus 3 weeks.
本研究调查了妊娠中期因高渗盐水引产的对象中胎儿大小（双顶径和头臀长）与孕周之间的关系。在90%的置信度下，双顶径可用于预测孕周，误差在正负2周内；头臀长可用于预测孕周，误差在正负3周内。
