Clinical assessment of gestational age at birth: the effects of sex, birthweight, and weight for length of gestation.

During studies on different aspects of fetal growth rate infants who were small-for-dates (SFD) large-for-dates (LFD) or within the normal range of birthweight for length of gestation (AFD) were examined within 48 h of birth. Gestational age was clinically assessed by the Dubowitz method. Among 140 AFD infants boys had higher mean values than girls for total and external scores, but there was no difference in neurological scores. Multiple regression of the score for external criteria on gestation, birthweight and sex, showed a significant contribution for birthweight and sex in addition to gestation; whereas gestation was the only singificant explanatory variable in the regression of the score for neurological criteria. When infants in the three weight groups were matched for length of gestation an sex, the SFD group had significantly lower mean total and external scores than the AFD group. The mean scores for the LFD group were not significantly higher than the AFD group. The neurological scores did not differ in the three groups. Maturation of external characteristics is related to weight as well as gestation. When assessment is made after birth by a clinical examination which includes these characteristics, the length of gestation of some SFD infants will be underestimated. The sex of the infant should also be borne in mind.