[The developmental characteristics of postterm fetuses assessed using both the physical parameters and real-time...

To evaluate how the physical profile differs between term and postterm fetuses, a statistical and an allometric analyses were made on 6658 cases delivered at 20 weeks of gestation or more in our hospital for last 40 years from 1940s to 1970s, by using the physical parameters such as the weight, the height and so on. Consequently, it was evident that there were two types of the postterm infants which were most markedly manifested on the body weight. One continued to grow and another remained less increasing in body weight. Unrelated to the weight at birth, the postterm infants were also found to have the transverse diameters (e.g. biparietal diameter) of the head which became more disproportionally enlarged than were those at term. This finding explains, in part, why the postterm fetus is susceptible to dystocia, and also implicates that the fetus will follow the brain development at 42 weeks of gestation onwards, as if it would run on such the same extrauterine course that the neonate given birth at term does so. A study was further extended to assess the functional aspect of the fetal development in association with the pathogenesis of the postterm fetuses, where three parameters including fetal urine production rate, fetal eye movement and resistance index (RI) at the umbilical arteries were used: The first and the second were observed using real-time ultrasound, and the third by means of pulse Doppler method.(ABSTRACT TRUNCATED AT 250 WORDS)