Levi S, Keuwez J, Reimers M, Jacques G, Awoust J, Alvarez H, Carton A
J Gynecol Obstet Biol Reprod (Paris). 1984;13(5):521-6.
From the end of the first trimester of pregnancy it is possible to recognize the sex of the fetus. The percentage with which this can be done rises progressively with the age of the fetus (from 29% at 18 weeks to 72% at 24 weeks), and with the experience of the operator. Errors are few; about between 1 and 2%. The number of errors in the ability to decide the sex is independent of which sex the fetus is. The body measurements show a difference between the made and the female fetuses which is statistically significant from the 20th week onwards. Growth tables which are specific for each sex can be made.
从妊娠头三个月末开始，就有可能识别胎儿的性别。能够做到这一点的比例会随着胎儿年龄的增长（从18周时的29%上升到24周时的72%）以及操作人员的经验而逐步提高。错误很少，大约在1%到2%之间。判断性别的错误数量与胎儿的性别无关。身体测量显示，从第20周起，男、女胎儿之间存在统计学上显著的差异。可以制定针对每种性别的生长图表。
