Short-Term Growth of Head Circumference in Healthy Infants

Abstract

In the last decade, studies based on daily or weekly measurements of stature in children have suggested that growth is a non-linear and discontinuous process. There are few data in the literature about the daily growth of head circumference (HC). With the purpose of evaluating HC patterns in healthy infants, we took replicate measurements in HC five times a week over a period of 150 days in 9 infants aged 0.32 to 0.84 years at the onset of the study. The technical error (TEM) varied between 0.08 and 0.15 cm. The smoothing technique used was based on the TEM, with a hard rejection criterion. We defined growth as any increment between two consecutive smoothed values higher than 6 times the expected deviation of such difference. Abrupt changes in HC (saltation) were arbitrarily defined as any daily increment greater than 0.3 cm. Results: Eight out of 9 infants showed saltatory growth. The number of days of stasis accounted for 68.5% of the total measurement period (150 days). The mean duration of each stasis period between growth episodes was 4.4 days and the longest period was of 45 consecutive days. The mean number of saltation periods was 2.5, and the largest amplitude was 0.80 cm in one single day. Saltation accounted for 37.2 % of the total growth during the study period. Conclusion: Our findings suggest that HC growth is a discontinuous and irregular process with three phases: stasis, continuous growth, and saltation. This is consistent with short-term growth of stature and lower leg length, and should contribute to the understanding of control and regulation mechanisms of infants growth.