Establishing the newborn and fetus age by taking into account of cervical vertebral bony parts dimensions is useful in anthropology and anthropometry as well. In the present study, we tried to determine some morphometric indices of fifth bony part's cervical vertebral arch in both fetus and newborn. We analyzed their correlation with the age of the subjects studied. We used a set of five newborn and five fetuses of six-seven months. We removed the fifth right cervical vertebral hemiarch from each subject. Images of vertebral bony parts hemiarches were acquisitioned, processed and measured by a morphometric Lucia M specialized soft. We measured the bony parts surface area, we traced the hemiarch frame triangle, and we measured the angles, the sides and the frame-triangle surface area, for each hemiarch. By analyzing the data we succeeded in revealing that the ratio between the anteromedial angle value and the opposite side length of that angle correlates to the fetus and newborn ages. Therefore, we consider this ratio as being an anthropometric index useful in deciding upon the fetus and newborn age.