Selbing A, Fjällbrant B
J Clin Ultrasound. 1984 Jul-Aug;12(6):343-6. doi: 10.1002/jcu.1870120606.
The accuracy of conceptual age estimated by crown-rump length is not fully assessed by Robinson and Fleming in their excellent study. They avoid the problem by using the expression "menstrual maturity." We have evaluated predictors of fetal age from crown-rump length measurements where conceptual age was calculated either from the day of artificial insemination by donor (AID) or from the day of ovulation as judged from recordings of basal body temperature (BBT). When the date of AID was used as the conception date, better mathematical fits (R2 = 0.92) were obtained than when the thermal nadir was used (R2 = 0.86). The distribution around the regression line in the AID group is skewed with the 5th-95th percentile range being 3.7 days above the line and 7.3 days below the line. Similar results were obtained in the BBT group. Possible reasons for these findings are discussed.
罗宾逊和弗莱明在其出色的研究中并未充分评估通过头臀长估计的概念年龄的准确性。他们通过使用“月经成熟度”这一表述来避免该问题。我们根据头臀长测量值评估了胎儿年龄的预测指标，其中概念年龄要么根据供体人工授精（AID）之日计算，要么根据基础体温（BBT）记录判断的排卵之日计算。当将AID日期用作受孕日期时，与使用体温最低点时相比，获得了更好的数学拟合度（R2 = 0.92）（R2 = 0.86）。AID组中回归线周围的分布呈偏态，第5至95百分位数范围在回归线之上为3.7天，在回归线之下为7.3天。在BBT组中也获得了类似结果。讨论了这些发现的可能原因。
