Aims
To evaluate the growth patterns of infants born large-for-gestational-age (LGA) from birth to age 1 year compared to those born appropriate-for-gestational-age (AGA). In addition, we aimed to investigate possible epigenetic changes associated with being born LGA.
Methods
Seventy-one singleton infants born at term were classified by birth weight as AGA (10th-90th percentile; n=42) and as LGA (>90th percentile; n=29). Post-natal follow-up until age 1 year was performed with clinical assessments at 3, 6, and 12 months. Assessments included measurement of infants’ weight, length, ponderal index, BMI, as well as head, chest, and abdominal circumference. A subgroup of 38 infants (17 AGA and 21 LGA) was selected for genome-wide DNA methylation analysis. Umbilical cord was collected at birth, and methylation profile on umbilical tissue was analysed using the Illumina Infinium 450K methylation array.
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Results
At birth, the LGA group had greater birth weight (P<0.0001), length (P<0.0001), head circumference (P<0.0001), ponderal index (P=0.02), BMI (P<0.0001), chest and abdominal circumferences (P=0.04 and P=0.007, respectively) than AGA newborns. At the age of 3 months, LGA infants still presented greater weight (P<0.0001), length (P=0.006), BMI (P=0.02), as well as head (P=0.004) and abdominal (P=0.04) circumferences than AGA peers. However, by age 6 months there were no more anthropometric differences between the two groups. This was due to higher length increment in AGA than LGA infants between 0-6 months (18.3 vs 15.1 cm; P<0.0001), whereas length increment was identical in both groups between 6-12 months (7.7 vs 7.7 cm; P=0.96). For the genome-wide analysis, more than 485,000 DNA methylation sites covering 99% of human NCBI Reference Sequence (RefSeq) genes were examined at birth, but no differences were found between LGA and AGA infants.
Conclusion
Despite being born oversized at birth, LGA infants displayed early catch-down growth (i.e. slower length velocity), so that by the age of 6 months LGA infants were of similar length and BMI as AGA infants. In addition, no epigenetic differences in genome-wide methylation were found in those born LGA.
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