Head Circumference within the Normal Range and Neurodevelopmental Outcomes in Preterm Infants.

OBJECTIVE: We sought to determine if variation in head circumference (HC) within the range of normal (5th-10th and 90th-95th percentile) is associated with poor neurodevelopmental outcomes (NDO), which defined as mild or moderate delay by Bayley II psychometrics (BSID-II). STUDY DESIGN: This is a secondary analysis of a randomized controlled trial assessing the benefits of magnesium for the prevention of cerebral palsy. Fetuses with a normal HC at birth defined as within 5th to 95th percentile were included. NDO were assessed at age 2 with BSID-II. Moderate delay was defined as a score <70 and mild delay as <85. HC was classified as small normal (5th-10th percentile), normal (10th-90th percentile), and large normal (90th-95th percentile). Logistic regression models adjusted for confounding. Linear regression models estimated the impact for every 1 cm of change in HC. RESULTS: Of 1,236 included infants, 111 (8%) had small normal HC; 1,058 (85%) had normal HC; and 67 (5%) had large normal HC. Baseline characteristics were similar between groups. There was no association with changes in HC within the range of normal and developmental indices. When considered as a continuous variable, every 1 cm increase in HC was also not associated with a significant change in developmental indices. CONCLUSION: Within the normal range (5th-95th percentile), changes in HC did not correlate with changes in NDO at 2 years as measured by Bayley II scales. KEY POINTS: · It is unknown if variations in normal HC are associated with poor neurodevelopmental outcomes.. · Alterations in HC within the range of normal (5th-95th percentile) are not associated with adverse NDO.. · When considered as a continuous variable, a 1 cm increase in HC is not associated with adverse NDO.. · Changes in HC within the range of normal do not appear to be a pathologic change altering NDO..