Growth in extremely low birth weight infants up to three years.

OBJECTIVE: To evaluate postnatal growth of extremely low birth weight infants (ELBW, <1,000 g) until 36 months of corrected age (CA), and to relate growth outcome to anthropometric parameters at birth, sex, fetal growth status (small or appropriate for gestational age--SGA/AGA), period of admission and major perinatal events. STUDY DESIGN/METHOD: Weight (Wt), height (Ht) and head circumference (HC) were assessed in 159 ELBW infants. Data were standardized with Z-scores following Usher and McLean and Sempe growth curves. Uni- and multivariate statistical analysis were performed. RESULTS: The mean birth weight was 851.2+/-116.5 g. Z-scores decreased from birth to term, at a deeper rate for AGA than for SGA infants (p<0.005 for Ht, Wt, and HC). Between term and 36 months, growth was better in SGA compared with AGA infants (p=0.003 for Ht). Multivariate analysis showed that anthropometric parameters at birth were positive determinants for Wt, Ht and HC at term, and also for Wt and Ht at 36 months CA (Z-scores). Oxygen therapy after 36 weeks of post-conceptional age was a negative determinant influencing growth at 36 months CA (Z-scores). CONCLUSIONS: Significant catch-up growth took place between birth and 36 months, which was greater for SGA than for AGA infants. Anthropometric parameters at birth and oxygen therapy at 36 weeks post-conceptional age are the main predictive factors for growth at 36 months CA.