van de Velde E H, Broeders G H, Horbach J G, Esser-Rath V W
Eur J Obstet Gynecol Reprod Biol. 1980 May;10(4):225-30. doi: 10.1016/0028-2243(80)90002-7.
In order to establish the reliability and accuracy of crown-rump length measurements of the fetus between the 7th and 14th wk of pregnancy, a series of 118 ultrasound tests has been performed on 60 patients, whose ovulation dates were known from basal body temperature records. During the tests, the investigator was not informed of the duration of the pregnancy. These data were statistically analyzed, using the equation t = 0.037 L2,24 (t is the duration of the pregnancy from the moment of ovulation onwards, L the crown-rump length in cm). The correlation coefficient was 0.942. This investigation proved that, if ultrasound measurements of the crown-rump length are taken in the first trimester, the maturity of the pregnancy can be estimated to within 1 wk.
为确定妊娠7至14周胎儿头臀长测量的可靠性和准确性，对60名患者进行了118次超声检查，这些患者的排卵日期可根据基础体温记录得知。检查期间，研究人员并不知晓妊娠时长。利用公式t = 0.037L².²⁴（t为自排卵起的妊娠时长，L为以厘米为单位的头臀长）对这些数据进行了统计分析。相关系数为0.942。该研究证明，如果在孕早期进行头臀长的超声测量，妊娠周数可估计在1周以内。
