[Gestational age and birth weight. 3. Ponderal Index, fetal acid-base metabolism and hypotrophy]

3rd communication: Ponderal-Index, fetal acid-base balance, acidotic risk and minimal placental weight (MPW). The Ponderal-Index of Rohrer (RI), the weight-centile of the newborn and the fetal weight-length-coefficient (FWLC) were evaluated and compared as to the correlation with the variables of the fetal acid-base balance. Using the example of continuous nicotine abuse in pregnancy, a new variable, the minimal placental weight (MPW), was defined. Its clinical applicability was preliminarily tested on the basis of selected cases. RI, FWLC and fetal weight-centiles show highly significant correlations with variables of the fetal acid-base balance. The closest statistical correlation was found for the fetal weight-centile. RI and FWLC did not proof to offer any advantages over this variable. The curve of the acidotic risk of the newborn showed a u-shaped distribution with maximum values in SGA-infants as well as macrosomic babies. Complex umbilical cord-entanglement were more frequently encountered in SGA-fetuses. Macrosomic infants did not show an increased risk in this respect. The preliminary data of this evaluation suggest a predictive value of the MPW for the acidotic risk of the newborn.