TABLE 1

Demographic Characteristics of the Study Sample

CharacteristicAge GroupP
8 Months (n = 110)18 Months (n = 100)30 Months (n = 96)
Gestational ageNS
 37–41 wk 43 (39)39 (39)37 (39)
 32–36 wk44 (40)41 (41)39 (41)
 <32 wk or <1500 g23 (21)20 (20)20 (21)
Gender< .05
 Female45 (41)47 (47)53 (55)*
 Male65 (59)53 (53)43 (45)*
Multiple pregnancies34 (31)31 (31)35 (37)NS
Maternal age, mean ± SD, y32.9 ± 3.634.2 ± 3.335.3 ± 4.2< .05**
Mother’s years of education17.7 ± 2.617.4 ± 2.317.6 ± 2.6NS
Maternal occupationNS
 Paid work717774
 Homemaker292326
Family income eighth and ninth deciles of income9595100NS
  • Data are presented as n (%), mean ± SD, or %. NS, not significant.

  • * P < .05 when comparing the 8-month-old group with the 30-month-old group.

  • ** All of the comparisons are significant (P < .05).