Table 2. Characteristics of women in ALSPAC in confounder-adjusted multivariable regression.
| Variable | Insomnia at 18 weeks of gestation (N = 10,540) | ||
|---|---|---|---|
| Yes | No | ||
| Mean (standard deviation) | |||
| Maternal age at delivery (years) | 27.1 (5.0) | 28.6 (4.7) | |
| Maternal height (cm) | 163.1 (6.8) | 164.3 (6.7) | |
| Maternal body mass index (kg/m2) | 23.4 (4.3) | 22.9 (3.7) | |
| Gestational age (weeks) | 39.5 (1.8) | 39.6 (1.7) | |
| Offspring birthweight (grams) | 3,409.0 (546.6) | 3,446.6 (522.4) | |
| N (%) | |||
| Insomnia at 32 weeks of gestation | Yes | 1,073 (10.2) | 1,984 (18.8) |
| No | 599 (5.7) | 6,781 (64.3) | |
| Maternal educationa | |||
| O levels/GCSEs or equivalent and below | 1,308 12.4 | 5,433 (51.5) | |
| A levels/AS levels or equivalent | 280 (2.7) | 2,126 (20.2) | |
| College or university degree | 95 (0.9) | 1,244 (11.8) | |
| Household occupational social class | |||
| I Professional occupations | 29 (0.3) | 288 (2.7) | |
| II Managerial and technical occupations | 240 (2.3) | 2,041 (19.4) | |
| III Skilled non-manual occupations | 353 (3.3) | 2,185 (20.7) | |
| III Skilled manual occupations | 515 (4.9) | 2,444 (23.2) | |
| IV Partly skilled occupations | 321 (3.0) | 1,221 (11.6) | |
| V Unskilled occupations | 106 (1.0) | 334 (3.2) | |
| Maternal smoking status in pregnancy | Ever | 590 (5.6) | 1,971 (18.7) |
| Never | 1,106 (10.5) | 6,873 (65.2) | |
| Maternal drinking status in pregnancy | Ever | 1,032 (9.8) | 5,968 (56.6) |
| Never | 539 (5.1) | 2,556 (24.3) | |
| Offspring sex | Male | 886 (8.4) | 4,539 (43.1) |
| Female | 810 (7.7) | 4,304 (40.8) | |
| GD | Case | 8 (0.1) | 36 (0.3) |
| Control | 1,538 (14.6) | 8,210 (77.9) | |
| HDP | Case | 295 (2.8) | 1,403 (13.3) |
| Control | 1,393 (13.2) | 7,389 (70.1) | |
| Perinatal depression | Case | 242 (2.3) | 460 (4.4) |
| Control | 1,207 (11.5) | 7,759 (73.6) | |
| PTB | Case | 79 (0.7) | 369 (3.5) |
| Control | 1,170 (11.1) | 6,324 (60.0) | |
| LBW | Case | 90 (0.9) | 421 (4.0) |
| Control | 1,578 (15.0) | 8,263 (78.4) | |
| HBW | Case | 28 (0.3) | 160 (1.5) |
| Control | 1,578 (15.0) | 8,263 (78.4) | |
aO level, General Certificate Education (GCE) Ordinary Level; GCSE, General Certificate of Secondary Education; A level, GCE Advanced level; AS level, GCE Advanced Subsidiary level.
ALSPAC, Avon Longitudinal Study of Parents and Children; GD, gestational diabetes; HBW, high offspring birthweight; HDP, hypertensive disorders of pregnancy; LBW, low offspring birthweight; PTB, preterm birth.