Early spontaneous catch-up growth.

We explored factors related to early catch-up growth in healthy children in Göteborg, Sweden. Most (82.9%) infants born small for gestational age (SGA) showed catch-up growth during their first 6 months, and 94.3% reached a final height within the normal range. At 6 months, 21 SGA children remained short and 45 non-SGA babies fell below the -2 SDS cutoff in height. Of these 66 short infants, 10 (15.2%) remained short into adulthood and 56 showed spontaneous catch-up growth. Fetal growth should be defined by body size at 6 months of age rather than at birth because most SGA infants catch up before 6 months, and furthermore, fetal growth regulatory mechanisms, such as insulin-like growth factor-I and -II, are the primary growth-promoting factors until 6 months of age.