Interrelations between early child development, gestational age and birth weight

Five traits of early child development were studied in 656 infants from the day of birth till 2 years of age. The infants selected for follow-up were born at 26-42 weeks of gestational age and with a birth weight accordingly ranging from 860 to 4560g. Analysis of variance was carried out for each of the following five traits which entailed the age at which a child: 1) turned himself over (turned); 2) sat unsupported for a few seconds (sat); 3) stood up (stood); 4) walked unsupported (walked); and 5) cut its first tooth (tooth). The results of this survey show no significant sex differences in the age of initial occurrence of any of the studied traits. Comparison with older siblings of the surveyed infants indicated a significant sibling resemblance component for all 5 trais, with the respective intraclass correlation coefficients ranging between 0.34 and 0.53. Gestational age and birth weight, but not "tooth", appeared to be important messages of an infant's motor development, insofar as onset of the studied traits. The separate correlations of "turned", "sat", "stood" and "walked" with gestational age or weight were all negative and statistically highly significant.