Alterations in head shape of newborn infants after caesarean section or vaginal delivery.

Alterations of head shape in preterm, small-for-dates, and term normal infants were studied by measuring occipitofrontal circumference (OFC), biparietal diameter (BPD), and occipitofrontal diameter (OFD) at intervals after birth. In 9 preterm infants born by elective caesarean section ther was a 5-2% reduction in BPD and 2-0% reduction in OFC at the age of 7 days. In 18 term infants born by elective caesarean section these changes were 2-4% and 0% respectively in BPD and OFC. In 25 preterm infants born by vertex vaginal delivery there was a significant fall in OFC of 0-7% at the age of 7 days and of 2-4% in BPD, but no significant change in OFD. In 19 small-for-dates infants born vaginally OFC increased 1-0% and OFD 2-7% at 7 days, but BPD decreased 2-5%. After the first week all three measurements increased in both groups of vaginal deliveries. The results show that shrinkage and biparietal flattening of the skull occur during the first week of life in preterm and term infants born by caesarean section and in preterm infants born vaginally. This fact should be borne in mind when comparing the measurements of an infant's head size with published norms.