to 3 years of life. A more recent study of children with birth weights less than 1,500 grams documented catch-up growth during the first 8 years of life, with poorer growth attainment among those who were small for gestational age (SGA) (Hack et al., 1996). Ford et al. (2000) also documented catch-up growth among children with birth weight less than 1,500 grams although they are still smaller than those born with normal birth weights. Another study also found that 18–19 year old boys with birth weights less than 1,500 grams were shorter and lighter than their counterparts with normal birth weights (Ericson and Kallen, 1998). Finally, Saigal and colleagues (2001) found that adolescents with birth weights less than 1,000 grams demonstrated patterns of catch-up growth between age 8 and adolescence.
Studies on the ultimate growth attainment or growth during the adolescent years and into early adulthood for individuals born preterm are only recently appearing in the literature. Doyle and colleagues (2004b) found compromised growth among survivors up to age 8 who were born with birth weights less than 1,000 grams, but by age 14 and up to age 20 they had reached average height and weight. Despite the persistence of lower height among survivors with birth weights less than 1,000 grams, Saigal and colleagues (2001) showed that most of their adolescents were within 2 standard deviations of the mean. Furthermore, Hack and colleagues (2003) documented gender differences. In childhood (8 years), males with birth weights less than 1,500 grams were shorter and lighter than counterparts with normal birth weight, whereas females were lighter but not significantly shorter than their counterparts with normal birth weights (Hack et al., 2003). The discrepancy for males persisted at 20 years, but females did not demonstrate subaverage height and weight at early adulthood (Hack et al., 2003). The predictors of height and weight also differed for males and females. For females, black race and chronic illness predicted weight, and maternal height and birthweight standardized score predicted height at 20 years of age (Hack et al., 2003). The predictors of height for males were the same as the females’ with duration of neonatal hospital stay and SGA birth as additional predictors of height (Hack et al., 2003).
Many of these findings suggest that by adolescence children born preterm experience catch-up growth. Since sexual maturation is an important aspect of adolescent development, studies on growth attainment for preterm infants during the adolescent years should evaluate sexual maturity. Another area for further research to elucidate the factors involved in catch-up growth among LBW survivors is nutrition. Weiler and colleagues (2002) found that despite the impact of preterm birth on attainment of normal height in young adulthood, bone mass is appropriate.