Weighted* descriptive statistics of maternal employment precarity by per cent of low and normal birth weight, NLSY79 cohort (1979–2007)
| Entire sample (n=2871) | Low birth weight (n=342) | Normal birth weight (n=2529) | ||||||
| N | % | N | % | N | % | |||
| Material rewards | High | 1102 | 44.0 | 129 | 79.6 | 973 | 37.7 | |
| Medium | 546 | 21.1 | 69 | 8.2 | 477 | 23.4 | ||
| Low | 891 | 30.1 | 105 | 9.0 | 786 | 34.0 | ||
| Missing | 332 | 4.7 | 39 | 3.2 | 293 | 5.0 | ||
| Income† | Upper 50% | 1354 | 60.5 | 159 | 83.3 | 1194 | 41.2 | |
| Lower 50% | 1358 | 37.2 | 164 | 14.9 | 1195 | 56.4 | ||
| Missing | 159 | 2.3 | 19 | 1.8 | 140 | 2.4 | ||
| Insurance | Yes | 1433 | 49.3 | 168 | 84.0 | 1265 | 43.1 | |
| No | 1258 | 48.3 | 151 | 14.3 | 1107 | 54.3 | ||
| Missing | 180 | 2.5 | 23 | 1.7 | 157 | 2.6 | ||
| Working time arrangements‡ | Regular | 1947 | 73.0 | 214 | 86.7 | 1733 | 70.5 | |
| Irregular | 796 | 24.4 | 114 | 12.6 | 682 | 26.5 | ||
| Missing | 128 | 2.7 | 14 | 0.7 | 114 | 3.0 | ||
| Shift | Day shift | 2185 | 79.8 | 256 | 91.7 | 1929 | 77.6 | |
| Not day shift | 558 | 17.6 | 72 | 7.6 | 486 | 19.4 | ||
| Missing | 128 | 2.7 | 14 | 0.7 | 114 | 3.0 | ||
| Hours per day | ≤8 | 2560 | 84.7 | 292 | 94.1 | 2268 | 83.0 | |
| >8 | 311 | 15.3 | 50 | 5.9 | 261 | 17.0 | ||
| Missing | 0 | 0 | 0 | 0 | 0 | 0 | ||
| Employability opportunities§ | Yes | 252 | 19.3 | 35 | 4.8 | 217 | 21.9 | |
| No | 2491 | 78.4 | 284 | 92.5 | 2207 | 75.9 | ||
| Missing | 128 | 2.3 | 23 | 2.7 | 105 | 2.2 | ||
| Collective organisation¶ | Yes | 220 | 3.7 | 31 | 3.3 | 189 | 3.7 | |
| No | 2496 | 93.7 | 297 | 95.1 | 2199 | 93.4 | ||
| Missing | 155 | 2.6 | 14 | 1.6 | 141 | 0.6 | ||
| Employment precarity** | Low | 1305 | 45.0 | 152 | 80.9 | 1153 | 38.6 | |
| Medium | 607 | 30.5 | 75 | 8.6 | 532 | 34.5 | ||
| High | 959 | 24.4 | 115 | 10.6 | 844 | 26.9 | ||
| Continuous | 2871 | – | 342 | – | 2529 | – | ||
| Missing | 0 | 0 | 0 | 0 | 0 | 0 | ||
*Sample weights derived from the Bureau of Labor Statistics National Longitudinal Surveys custom weighting programme; means, SE and percentages are weighted, N’s are unweighted.
†Income was adjusted for inflation to the 1979 dollar value.
‡Women with regular working times had a day shift and worked ≤8 hours per day. Women with irregular working times had a non-day shift or worked more than 8 hours per day or had both.
§Employability opportunities was defined as having employer-provided trainings or education.
¶Collective organisation was defined as union membership.
**Employment precarity was categorised based on scores from an index of individual employment characteristics; low: 0–2, medium: 3, high: 4–6.
NLSY79, National Longitudinal Survey of Youth 1979.