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Plagiocephaly and brachycephaly in the first two years of life: a prospective cohort study
B Lynne Hutchison1, Luke A D Hutchison, John M D Thompson
1Department of Paediatrics, University of Auckland, Private Bag 92019, Auckland, New Zealand. bl.hutchison@auckland.ac.nz
Insights
Nonsynostotic plagiocephaly (NSP) prevalence peaks at 4 months in infants but often resolves by 2 years. Key infant risk factors include limited head rotation and supine sleep position.
Area of Science:
- Pediatric Health
- Infant Development
- Cranial Morphology
Background:
- Referrals for nonsynostotic plagiocephaly (NSP) have risen, yet its prevalence, natural history, and contributing factors remain unclear.
- Understanding NSP is crucial for infant care and developmental monitoring.
Purpose of the Study:
- To determine the prevalence and natural history of NSP in healthy infants up to 2 years of age.
- To identify factors associated with the development of NSP.
Main Methods:
- Digital photography and custom software quantified head shape in 200 infants from birth to 2 years.
- Infants were classified as cases based on cephalic index and oblique cranial length ratio.
- Assessed factors included neck rotation, infant care practices, and socioeconomic/obstetric variables.
Main Results:
- NSP prevalence was 16.0% at 6 weeks, peaking at 19.7% at 4 months, and decreasing to 3.3% by 2 years.
- Significant risk factors identified include limited passive/active head rotation, supine sleep position, and lower infant activity levels.
- Male gender and firstborn status were also associated with NSP at 4 months.
Conclusions:
- Infant head shapes vary widely, with NSP prevalence increasing in early infancy but generally resolving by age 2.
- Limited head rotation, reduced activity, and supine sleep position are key determinants of NSP.
- Most NSP cases resolve naturally, highlighting the importance of monitoring and early identification of risk factors.
Objectives:
Although referrals for nonsynostotic plagiocephaly (NSP) have increased in recent years, the prevalence, natural history, and determinants of the condition have been unclear. The objective of this study was to assess the prevalence and natural history of NSP in normal infants in the first 2 years of life and to identify factors that may contribute to the development of NSP.
Methods:
Two hundred infants were recruited at birth. At 6 weeks, 4 months, 8 months, 12 months, and 2 years, the head circumference shape was digitally photographed, and head shape was quantified using custom-written software. At each age, infants were classified as cases when the cephalic index was > or =93% and/or the oblique cranial length ratio was > or =106%. Neck rotation and a range of infant, infant care, socioeconomic, and obstetric factors were assessed.
Results:
Ninety-six percent of infants were followed to 12 months, and 90.5% were followed to 2 years. Prevalence of plagiocephaly and/or brachycephaly at 6 weeks and 4, 8, 12, and 24 months was 16.0%, 19.7%, 9.2%, 6.8%, and 3.3% respectively. The mean cephalic index by 2 years was 81.6% (range: 72.0%-102.6%); the mean oblique cranial length ratio was 102.6% (range: 100.1%-109.4%). Significant univariate risk factors of NSP at 6 weeks include limited passive neck rotation at birth, preferential head orientation, supine sleep position, and head position not varied when put to sleep. At 4 months, risk factors were male gender, firstborn, limited passive neck rotation at birth, limited active head rotation at 4 months, supine sleeping at birth and 6 weeks, lower activity level, and trying unsuccessfully to vary the head position when putting the infant down to sleep.
Conclusions:
There is a wide range of head shapes in infants, and prevalence of NSP increases to 4 months but diminishes as infants grow older. The majority of cases will have resolved by 2 years of age. Limited head rotation, lower activity levels, and supine sleep position seem to be important determinants.
