Small for gestational age, term babies, in the first six years of life

Abstract

The cognitive development and behaviour in the first six years of life of small for gestational age (SGA) babies born at term are reviewed. Differences in sample selection and confounding factors associated with socio-economic background, perinatal complications and biased follow-up make the interpretation of results and the comparison of studies difficult. Studies of infants (< 12 months) generally do not show any differences between SGA babies and controls. One study, carried out in Brazil and including comprehensive data on socio-economic background, parental literacy and infant stimulation, showed that low birth weight (LBW) babies were more vulnerable to effects of the environment than normal birth weight (NBW) babies, thus illustrating the importance of looking for interactions between covariates, rather than controlling for them. Deficits begin to appear in the second year of life, but are mainly found in high-risk subgroups. In all three studies of SGA children tested at 3 years of age, the SGA children had lower scores than NBW controls. SGA children tested between 4 and 7 years had generally lower scores than NBW, but differences were smaller and sometimes did no longer reach statistically significant levels. Some recommendations are made for future studies.

PIP: An estimated 16% of births worldwide are low birth weight (LBW); 90% of such infants are in developing, low-income countries. A greater proportion of LBW infants in low-income countries is reported to be small for gestational age (SGA) compared to in developed countries. The subsequent development of such children is critically important to both the future of the children and the countries they will inherit. Findings are reported from a review of the literature on the cognitive development and behavior during the first 6 years of life of SGA infants born at term. 6 studies were found of term, SGA infants in whom development was assessed during the first 2 years of life. Several of these studies followed the children beyond age 2 years and up to age 7. Differences in sample selection and confounding factors associated with socioeconomic background, perinatal complications, and biased follow-up complicate the interpretation of results and the comparison of studies. Nonetheless, the observed studies of infants under age 12 months generally show no differences between SGA subjects and controls. Deficits, however, in development begin to appear during the second year of life, but were found mainly in high-risk subgroups. In all 3 studies of SGA children tested at age 3 years, the SGA children had lower scores than did normal birth weight (NBW) controls. SGA children tested between ages 4 and 7 years had generally lower scores than NBW children, but differences were smaller and sometimes no longer statistically significant. One study conducted in Brazil is discussed in some detail.