Objectives To compare head shape measurements, parental concern about head shape and developmental delays in infancy with measurements obtained at follow-up at ages 3 and 4 years.

Design Longitudinal cohort study.

Setting Initial assessments were conducted at a plagiocephaly clinic; follow-up assessments were conducted in the children's homes.

Participants 129 children with a mean age of 4 years (range 3 years 3 months to 4 years 9 months), all of whom were diagnosed in infancy with deformational plagiocephaly or brachycephaly.

Main outcome measures Head shape measurements of cephalic index and oblique cranial length ratio; level of parental concern about head shape; and delays on parent-completed age-appropriate Ages and Stages Questionnaires.

Results 61% of head shape measurements reverted to the normal range; 4% remained severe at follow-up. Brachycephaly improved more than plagiocephaly. Facial and frontal asymmetry reduced to almost nil. Most had good improvement, but 13% were categorised as having ‘poor improvement’. Initially, 85% of parents reported being ‘somewhat’ or ‘very’ concerned; this decreased to 13% at follow-up. The percentage of children with ≥1 delay decreased from 41% initially to 11% at follow-up.

Conclusions Overall, head shape measurements, parental concern and developmental delays in infancy showed a dramatic improvement when re-measured at 3 and 4 years of age.