Egley C C, Seeds J W, Cefalo R C
Am J Perinatol. 1986 Apr;3(2):77-9. doi: 10.1055/s-2007-999837.
It is well established that ultrasound measurement of femur length and biparietal diameter are comparably accurate estimators of gestational age when obtained in the first half of pregnancy. Both estimators, however, become less accurate later in pregnancy. The present study compares the relative accuracy of these estimators when obtained in the third trimester. It is concluded from linear regression analysis that the correlation between gestational age estimated from femur length and the actual gestational age is stronger than that between gestational age estimated from biparietal diameter and actual gestational age. Furthermore, gestational age calculated from femur length is significantly more likely to be within 2 weeks (P less than or equal to .01) and 3 weeks (P less than or equal to .05) of actual gestational age than is gestational age calculated from biparietal diameter. Estimating gestational age from the mean of the gestational age based on biparietal diameter and that based on femur length is less accurate than estimating gestational age from femur length alone.
众所周知，在妊娠前半期进行超声测量股骨长度和双顶径是相当准确的孕周估计指标。然而，这两个指标在妊娠后期的准确性都会降低。本研究比较了在妊娠晚期获得这些指标时的相对准确性。线性回归分析得出的结论是，根据股骨长度估计的孕周与实际孕周之间的相关性强于根据双顶径估计的孕周与实际孕周之间的相关性。此外，与根据双顶径计算的孕周相比，根据股骨长度计算的孕周更有可能在实际孕周的2周内（P≤0.01）和3周内（P≤0.05）。根据双顶径和股骨长度估计的孕周平均值来估计孕周，其准确性低于仅根据股骨长度来估计孕周。
