Fetal bone age revisited: proposal of a new radiographic score.

In order to establish a fetal bone age score, the post-mortem skeletal radiographs of 85 selected normal fetuses aged from 15 to 41 weeks of gestation (WG) were analysed. Twenty-eight skeletal areas were selected for which quantitative and/or qualitative criteria were defined. Each new aspect was graded and statistically tested by the stepwise linear regression method. Two modalities of scores and decreasing complexity were then designed. The use of these two scores permitted the assessment of the fetal age with r2 values of 0.97 and 0.96 (standard error of estimation of 1.19 and 1.36 WG). Applied to 15 intrauterine growth retardation (IUGR) fetuses, the age estimated by these scores was well correlated with the age obtained by extraosseous criteria of maturation. This method is proposed as a tool for determining, the fetal age during necropsy and could also be useful in US prenatal evaluation.