Campbell S, Thoms A
Br J Obstet Gynaecol. 1977 Mar;84(3):165-74. doi: 10.1111/j.1471-0528.1977.tb12550.x.
Fetal head and abdomen circumference measurements have been made using pulsed ultrasound techniques. The mean head to abdomen (H/A) circumference ratio with 95% confidence limits was determined in 568 normal pregnancies from 17 to 41 weeks menstrual age. The mean ratio was 1-18 at 17 weeks, but decreased slowly until 29 weeks when the ratio was 1-11; thereafter there was a sharp fall in the mean ratio to 1-01 at 36 weeks and 0-96 at 40 weeks. The H/A circumference ratio was also determined in 31 small-for-dates fetuses within one week of delivery. In all cases the fetal weight as predicted from the fetal abdomen circumference measurement was below the 5th centile weight for gestation. The ratio was above the 95th centile limit in 22 (71%) of these fetuses and evidence is presented to suggest that the H/A circumference ratio can be used to distinguish between symmetrical and asymmetrical growth retardation.
已使用脉冲超声技术测量胎儿头部和腹部周长。在568例月经龄为17至41周的正常妊娠中，确定了头腹（H/A）周长平均比值及其95%置信区间。17周时平均比值为1.18，但缓慢下降，至29周时比值为1.11；此后平均比值急剧下降，36周时为1.01，40周时为0.96。在31例足月小样儿分娩前一周内也测定了H/A周长比值。所有病例中，根据胎儿腹部周长测量预测的胎儿体重均低于该孕周体重的第5百分位数。这些胎儿中有22例（71%）的比值高于第95百分位数界限，有证据表明H/A周长比值可用于区分对称性和不对称性生长受限。
