Table 1.

Distribution of Sociodemographic Characteristics of Subjects According to Study Site Grouping

CharacteristicUrban (634)Study Site Grouping (n)Total (2253)
Small Town/Rural (951)Suburban (668)
Number (%) of subjects
Sex
 Male307 (48.4)507 (53.3)366 (54.8)1180 (52.4)
 Female327 (51.6)444 (46.7)302 (45.2)1073 (47.6)
Race
 White166 (26.2)928 (97.6)664 (99.4)1758 (78.0)
 Black438 (69.1)17 (1.8)4 (0.6)459 (20.4)
 Other/uncertain30 (4.7)6 (0.6)36 (1.6)
Birth weight, lb
 ≥5, <665 (10.3)46 (4.8)42 (6.3)153 (6.8)
 ≥6, <7213 (33.6)180 (18.9)123 (18.4)516 (22.9)
 ≥7, <8222 (35.0)373 (39.2)230 (34.4)825 (36.6)
 ≥8, <9100 (15.8)249 (26.2)186 (27.8)535 (23.7)
 ≥934 (5.4)103 (10.8)87 (13.0)224 (9.9)
Maternal age, y
 ≥18, <20104 (16.4)50 (5.3)3 (0.4)157 (7.0)
 20–24270 (42.6)270 (28.4)43 (6.4)583 (25.9)
 25–29164 (25.9)323 (34.0)217 (32.5)704 (31.3)
 30–3465 (10.3)225 (23.7)278 (41.6)568 (25.2)
 ≥3531 (4.9)83 (8.7)127 (19.0)241 (10.7)
Season of birth
 Winter126 (19.9)254 (26.7)127 (19.0)507 (22.5)
 Spring164 (25.9)215 (22.6)175 (26.2)554 (24.6)
 Summer186 (29.3)237 (24.9)207 (31.0)630 (28.0)
 Fall158 (24.9)245 (25.8)159 (23.8)562 (24.9)
Maternal education
 <High school118 (18.6)53 (5.6)6 (0.9)177 (7.9)
 High school256 (40.4)425 (44.7)173 (25.9)854 (37.9)
 Technical/associate238 (37.5)335 (35.2)238 (35.6)811 (36.0)
 College graduate19 (3.0)116 (12.2)178 (26.6)313 (13.9)
 Postgraduate3 (0.5)22 (2.3)73 (10.9)98 (4.3)
Health insurance status
 Private35 (5.5)614 (64.6)640 (95.8)1289 (57.2)
 Medicaid590 (93.1)322 (33.9)18 (2.7)930 (41.3)
 None9 (1.4)15 (1.6)10 (1.5)34 (1.5)
Not breastfed at 2 mo568 (89.6)669 (70.3)392 (58.7)1629 (72.3)
Breastfed until 2 mo14 (2.2)64 (6.7)59 (8.8)137 (6.1)
 4 mo10 (1.6)56 (5.9)55 (8.2)121 (5.4)
 6 mo10 (1.6)38 (4.0)35 (5.2)83 (3.7)
 8 mo19 (3.0)66 (6.9)71 (10.6)156 (6.9)
 ≥12 mo13 (2.1)58 (6.1)56 (8.4)127 (5.6)
No. of smokers in household*
 0287 (45.4)602 (63.9)504 (75.4)1393 (62.1)
 1222 (35.1)229 (24.3)116 (17.4)567 (25.3)
 297 (15.3)101 (10.7)46 (6.9)244 (10.9)
 ≥326 (4.1)10 (1.1)2 (0.3)38 (1.7)
No. of other children in household
 0247 (39.0)391 (41.1)248 (37.1)886 (39.3)
 1210 (33.2)346 (36.4)264 (39.5)820 (36.4)
 2118 (18.6)162 (17.0)118 (17.7)398 (17.7)
 339 (6.2)38 (4.0)31 (4.6)108 (4.8)
 ≥419 (3.0)14 (1.5)7 (1.0)40 (1.8)
Day care mode first year of life
 None554 (87.4)728 (76.6)478 (71.6)1760 (78.1)
 Day care with no other children6 (0.9)59 (6.2)41 (6.1)106 (4.7)
 <5 other children40 (6.3)133 (14.0)95 (14.2)268 (11.9)
 ≥5 other children34 (5.4)31 (3.3)54 (8.1)119 (5.3)
 Day care <10 h/wk5 (0.8)12 (1.3)15 (2.2)32 (1.4)
 10 to 20 h/wk16 (2.5)52 (5.5)44 (6.6)112 (5.0)
 >20 h/wk59 (9.3)159 (16.7)131 (19.6)349 (15.5)
Day care mode second year of life
 None498 (78.5)685 (72.0)490 (73.3)1673 (74.3)
 Day care with no other children17 (2.7)72 (7.6)28 (4.2)117 (5.2)
 <5 other children61 (9.6)138 (14.5)88 (13.2)287 (12.7)
 ≥5 other children58 (9.1)56 (5.9)62 (9.3)176 (7.8)
 Day care <10 h/wk7 (1.1)23 (2.4)21 (3.1)51 (2.3)
 10 to 20 h/wk25 (3.9)70 (7.4)42 (6.3)137 (6.1)
 >20 h/wk104 (16.4)173 (18.2)115 (17.2)392 (17.4)
  • * Data missing for 11 subjects.

  • Data missing for one subject.

  • Modal (most commonly occurring) value in the course of a year for number of hours, and the associated modal value for number of children.