Drumm J E
Br J Obstet Gynaecol. 1977 Jan;84(1):1-5. doi: 10.1111/j.1471-0528.1977.tb12457.x.
The ultrasonic measurement of the fetal crown-rump lenght (CRL) in early pregnancy was utilized to predict the date of delivery in 220 patients with reliable menstrucal histories and in 186 patients with unreliable menstrual dates who began labour spontaneously; Ninety-five per cent and 96.2 per cent respectively were delivered within 12 days of the predicted date. The CRL was found to be better than biparietal diameter measurements (p greater than 0.001) and as good as a reliable menstrual history (p greater than 0.5) in predicting the time fo spontaneous onset of labour.
超声测量早孕时胎儿头臀长度（CRL），用于预测220例月经史可靠和186例月经日期不可靠但自然分娩患者的分娩日期；分别有95%和96.2%的患者在预测日期的12天内分娩。研究发现，在预测自然分娩时间方面，CRL比双顶径测量更具优势（p＞0.001），且与可靠的月经史效果相当（p＞0.5）。
