Small-for-gestational-age (SGA) infants born at term: growth and development during the first year of life.

Background: The purpose was to compare growth patterns and psychomotor development of healthy small-for-gestational-age (SGA) and non-SGA infants, and identify factors predictive of outcome at 13 months of age.

Method: A total of 265 SGA infants and 329 non-SGA controls were identified from a multicenter cohort of 5722 para 1 and 2 women who had been followed during pregnancy. The infants were examined at 2 days and at 13 months of age. Psychomotor development at 13 months was assessed with The Bayley Scale of Infant Development.

Results: The SGA infants showed partial catch-up growth, but had still lower (mean +/- SEM, p < 0.0001) weight (9750 +/- 65 vs 10505 +/- 67 g), crown-heel length (75.9 +/- 0.2 vs 77.5 +/- 0.2 cm) and head circumference (46.9 +/- 0.1 vs 47.7 +/- 0.1 cm) than the non-SGA infants at 13 months. The SGA children scored equally well on the motor (PDI 106.8 +/- 1.0 vs 107.2 +/- 0.8) but lower on the mental scale (MDI 112.1 +/- 0.8 vs 116.5 +/- 0.7, p < 0.0001) of the Bayley Scale, and the asymmetric SGA scored lower than the symmetric SGA infants (MDI 110.2 +/- 1.3 vs 113.3 +/- 0.9, p = 0.05). In a multivariate regression analysis the parents' growth parameters had the greatest effect on growth measures at 13 months while education and maternal smoking had no significant effect. SGA vs non-SGA status had the greatest effect on growth velocities during infancy. For mental development only SGA vs non-SGA status and the mothers' education made significant contributions, but only accounted for 6% of the variance.

Conclusion: The negative impact of intrauterine factors on growth are partly abolished by catch-up growth during infancy, and growth parameters at one year of age are mostly determined by genetic factors even in SGA infants. Decreased intrauterine growth may possibly have a negative effect on brain growth and mental developmental potential.