Umbilical blood flow and neonatal morphometry: a multivariate analysis

To study the relation between the state of umbilical blood flow and neonatal morphometry.

We have recorded data from 460 pregnant women. Umbilical systolic to diastolic ratio was measured within the 3 days prior to the birth. Weight, height, head and chest circumferences, ponderal and head to chest circumferences ratio were considered for the study.

In a univariate analysis, the best correlated variable to S/D ratio was the weight (r=-0.35). However, a forward stepwise multiple regression analysis demonstrated that the best predictors of S/D ratio were height and ponderal index. Small-for-gestational-age fetuses with placental insufficiency (n=20) had a significant more pronounced decrease of weight, height, head circumference and chest circumference than those with normal placental perfusion (n=31). The degree of decrease of ponderal index and HC/TC was similar in both groups.

Umbilical blood flow is one important factor determining newborn morphometry. If only one growth variable is considered, the best correlation with umbilical S/D ratio is found to be the weight. The multivariate regression analysis concluded that the two most influential factors by umbilical blood flow are height and ponderal index and the rest of the morphometric parameters lost their significant correlations when adjusted by these variables. The impairment on neonatal morphometry in small-for-gestational-age fetuses associated to placental insufficiency is more severe than that with normal placental perfusion. However, it does not have a more pronounced decrease of ponderal index than the rest of causes of small-for-gestational-age fetuses.