Postnatal overestimation of gestational age in preterm infants.

In a study involving 25 preterm infants, obstetric clinical age (standard gestational age) was determined by history, physical examination, and ultrasonographic evaluation. Postnatally, these infants were then evaluated using the Dubowitz Scoring System (DSS) for gestational age assessment. The DSS, as administered by us, significantly overestimated gestational age compared with the standard gestational age (mean +/- 1 SD: 34.2 +/- 2.9 vs 32.5 +/- 3.9 weeks, respectively) in preterm infants. To illustrate, the gestational ages of 13 newborns (52%) in the total study group were each overestimated by more than two weeks. This percentage increased to 75% among the 16 infants whose gestational ages were less than 34 weeks (by standard gestational age). When the standard gestational age was underestimated by the DSS, this difference never exceeded two weeks. These findings suggest that the present system of postnatal assessment of gestational age in preterm infants needs further investigation.