Table 1. Demographic Characteristics by Maternal Going-to-Sleep Position in Control Participants.
| Characteristic | Maternal Going-to-Sleep Position | P Value | |
|---|---|---|---|
| Nonsupine | Supine | ||
| No. (%) | 1703 (96.8) | 57 (3.2) | |
| Individual study | |||
| Auckland | 288 (96.3) | 11 (3.7) | .38 |
| Sydney | 182 (98.4) | 3 (1.6) | |
| New Zealand | 541 (95.6) | 15 (4.4) | |
| England | 692 (96.1) | 28 (3.9) | |
| Age, mean (SD), y | 30.3 (5.5) | 29.6 (5.5) | .38 |
| Earliest pregnancy BMI, median (IQR) | 24.6 (22.0-29.0) | 24.0 (21.0-28.7) | .95 |
| Ethnicity, No. (%) | |||
| White | 1074 (97.2) | 31 (2.8) | .28 |
| Black | 35 (97.2) | 1 (2.8) | |
| South Asian | 202 (95.7) | 9 (4.3) | |
| Southeast or East Asian | 104 (95.4) | 5 (4.6) | |
| Maori | 104 (98.1) | 2 (1.9) | |
| Pacific Islander | 143 (94.1) | 9 (5.9) | |
| Other ethnicities | 41 (100) | 0 | |
| Parity, No. (%) | |||
| 0 | 749 (97.5) | 19 (2.5) | .006 |
| 1 | 604 (95.0) | 32 (5.0) | |
| ≥2 | 350 (98.3) | 6 (1.7) | |
| Education, No. (%) | |||
| Primary and/or secondary school | 554 (95.5) | 26 (4.5) | .12 |
| Trade school | 220 (97.3) | 6 (2.7) | |
| Tertiary—university and postgraduate | 929 (97.4) | 25 (2.6) | |
| Marital status, No. (%) | |||
| Single | 118 (92.2) | 10 (7.8) | .002 |
| Married or cohabiting | 1585 (97.1) | 47 (2.9) | |
| Preexisting hypertension or diabetes, No. (%) | 20 (95.2) | 1 (4.8) | .50 |
| Maternal smoking beyond the first trimester, No. (%) | 178 (97.8) | 4 (2.2) | .52 |
| Recreational drug use during pregnancy, No. (%) | 33 (100) | 0 | .33 |
| Gestation at interview, mean (SD), wk | 36.5 (3.5) | 35.5 (3.9) | .03 |
| Gestation at birth, mean (SD), wk | 40.0 (1.4) | 40.0 (1.4) | .87 |
Abbreviations: BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); IQR, interquartile range.