Table 1 Baseline demographics of the study subjects
Total (n = 1113) | Non-HD (n = 717, 64.4%) | HD (n = 396, 35.6%) | P value | |
|---|---|---|---|---|
Maternal age (years), mean (SD) | 31.16 (3.5) | 31.38 (3.5) | 30.76 (3.4) | 0.046 |
Paternal age (years), mean (SD) | 33.61 (3.8) | 33.71 (3.9) | 33.43 (3.7) | 0.051 |
Birth weight (kg), mean (SD)a | 3.26 (0.42) | 3.25 (0.42) | 3.28 (0.41) | 0.654 |
Gender, n (%) | 0.896 | |||
Boy | 562 (50.5) | 361 (50.3) | 201 (50.8) | |
Girl | 551 (49.5) | 356 (49.7) | 195 (49.2) | |
Infant’s birth order, n (%) | 0.323 | |||
Firstborn | 554 (49.8) | 349 (48.7) | 205 (51.8) | |
Later-born | 559 (50.2) | 368 (51.3) | 191 (48.2) | |
Household income, n (%)b | 0.191 | |||
I (<1639US$) | 302 (27.2) | 191 (26.6) | 111 (28.1) | |
II (1639–2458US$) | 384 (34.5) | 250 (34.9) | 134 (33.9) | |
III (2459–3278US$) | 226 (20.3) | 136 (19.0) | 90 (22.8) | |
IV(>3279US$) | 200 (18.0) | 140 (19.5) | 60 (15.2) | |
Maternal education level, n (%) | 0.176 | |||
High school | 341 (30.6) | 223 (31.1) | 118 (29.8) | |
College | 328 (29.5) | 198 (27.6) | 130 (32.8) | |
University | 444 (39.9) | 295 (41.3) | 148 (37.4) | |
Maternal smoking, n (%) | 0.148 | |||
No | 1084 (97.4) | 702 (97.9) | 382 (96.5) | |
Yes | 29 (2.6) | 15 (2.1) | 14 (3.5) | |
Maternal alcohol drinking, n (%) | 0.784 | |||
No | 467 (42.0) | 303 (42.3) | 164 (41.4) | |
Yes | 646 (58.0) | 414 (57.7) | 232 (58.6) | |
Paternal education level, n (%) | 0.582 | |||
High school | 297 (26.7) | 184 (25.4) | 113 (28.5) | |
College | 264 (23.7) | 172 (24.0) | 92 (23.2) | |
University | 552 (49.6) | 361 (50.3) | 191 (48.2) | |
Paternal smoking, n (%)c | 0.540 | |||
No | 558 (50.2) | 365 (50.9) | 193 (49.0) | |
Yes | 553 (49.8) | 352 (49.1) | 201 (51.0) | |
Paternal alcohol drinking, n (%)d | 0.388 | |||
No | 240 (21.8) | 161 (22.6) | 79 (20.4) | |
Yes | 860 (78.2) | 551 (77.4) | 309 (79.6) |