Iffy L, Jakobovits A, Westlake W, Wingate M, Caterini H, Kanofsky P, Menduke H
Pediatrics. 1975 Aug;56(2):173-86.
Liberalization of abortion laws in various countries and states of Europe and America has offered an opportunity for the study of the correlations between menstrual age and the rate of bodily development of human embryos and fetuses. In several institutions where local bylaws mandated the consent of the patients requesting therapeutic abortion to pathological investigation of the products of conception, various parameters of growth were measured systematically. These included crown-rump and foot lengths and body weight. The analysis of the data indicated that in the embryosic stages of development the rate of growth is substantially slower than it had been assumed previously. In the more advanced fetal stages of development the findings supported the validity of the long-established standard of Streeter. Since the current study has been based on apparently normal gestations of healthy women, whereas earlier data had rested, to a great extent, on spontaneously aborted and extopic embryon and fetuses, it seems evident that pathological specimens are not suitable for the purpose of establishing reliable standards of normal intrauterine growth rate. The present data support the suggestion, based on various experimental and clinical observations, that pathological gestations often result from abnormal ovulations that occur at times other than the mid-cycle and that such conceptions are frequently followed by a bleeding episode that simulates menstruation. It is likely that the inclusion of a high number of such cases biased the results of earlier investigations concerning embryonic growth rate on account of the frequent incidence of erroneous menstrual histories. The material available did not permit the extension of the investigation beyond the 20th week of gestation. It appears, however, that the average growth rate in the mid-trimester may be slower than the data adopted by the American Academy of Pediatrics would indicate. The possible causes of some phenomena observed in the course of the investigation, such as unexplained scatter of growth-rate patterns at all developmental stages and discrepancies among various literary data, have been discussed in some detail. While a tentative attempt has been made to correlate the investigated parameters of fetal growth with biparietal diameters of the head, a measurement accessible to direct assessment by sonography during pregnancy, the necessity of improving these standards through a prospective study has been emphasized.
欧美各国及各邦堕胎法的放宽为研究月经龄与人类胚胎及胎儿身体发育速率之间的相关性提供了契机。在一些地方法规要求请求治疗性堕胎的患者同意对妊娠产物进行病理检查的机构中，系统地测量了各种生长参数。这些参数包括顶臀长度、足长和体重。数据分析表明，在胚胎发育阶段，生长速率比之前假设的要慢得多。在胎儿发育的更高级阶段，研究结果支持了长期确立的斯特里特标准的有效性。由于当前的研究基于健康女性明显正常的妊娠，而早期数据在很大程度上基于自然流产和异位胚胎及胎儿，显然病理标本不适合用于确立正常宫内生长速率的可靠标准。目前的数据支持基于各种实验和临床观察得出的建议，即病理妊娠通常源于非月经周期中期发生的异常排卵，并且此类妊娠之后常常会出现类似月经的出血事件。很可能由于错误月经史的频繁发生，纳入大量此类病例使早期关于胚胎生长速率的研究结果产生了偏差。现有的材料不允许将研究扩展到妊娠第20周之后。然而，似乎孕中期的平均生长速率可能比美国儿科学会采用的数据所显示的要慢。已经详细讨论了在研究过程中观察到的一些现象的可能原因，例如在所有发育阶段生长速率模式的无法解释的离散以及各种文献数据之间的差异。虽然已经尝试将所研究的胎儿生长参数与头部双顶径相关联（双顶径是孕期可通过超声直接评估的测量值），但强调了通过前瞻性研究改进这些标准的必要性。
