Table 2.
Infant and maternal characteristics among singleton Juvenile Idiopathic Arthritis (JIA) cases and controls born in WA State, 1997–2010
| Characteristics | Cases (N = 1,234) | Controls (N = 5,993) | ||||
|---|---|---|---|---|---|---|
| n | % | N | % | ORa | 95% CI | |
| Infant factors | ||||||
| Gestational age (weeks) | ||||||
| < 37 | 72 | 6.0 | 352 | 6.0 | 0.99 | 0.76, 1.29 |
| 37–42 | 1,030 | 85.5 | 4,903 | 83.9 | 1.00 | reference |
| 42+ | 102 | 8.5 | 587 | 10.1 | 0.88 | 0.70, 1.10 |
| Size for gestational age | ||||||
| SGA | 102 | 9.4 | 496 | 9.6 | 1.01 | 0.81, 1.27 |
| AGA | 878 | 80.5 | 4,181 | 80.8 | 1.00 | reference |
| LGA | 110 | 10.1 | 500 | 9.6 | 1.01 | 0.81, 1.26 |
| Birth weight (grams) | ||||||
| < 2500 | 64 | 5.2 | 292 | 4.9 | 1.05 | 0.79, 1.39 |
| 2500–3999 | 1,026 | 83.3 | 4,880 | 81.7 | 1.00 | reference |
| ≥ 4000 | 142 | 11.5 | 803 | 13.4 | 0.81 | 0.67, 0.98 |
| Maternal factors | ||||||
| Cesarean Section | ||||||
| Yes | 256 | 20.7 | 1,110 | 18.5 | 1.08 | 0.93, 1.26 |
| No | 978 | 79.3 | 4,878 | 81.5 | 1.00 | reference |
| Number of prior birthsb | ||||||
| 0 | 525 | 43.6 | 2,488 | 42.5 | 1.00 | reference |
| 1 | 418 | 34.7 | 1,893 | 32.3 | 0.95 | 0.82, 1.10 |
| 2 | 157 | 13.0 | 931 | 15.9 | 0.68 | 0.56, 0.83 |
| 3 | 60 | 5.0 | 325 | 5.6 | 0.71 | 0.53, 0.96 |
| 4+ | 44 | 3.7 | 216 | 3.7 | 0.72 | 0.51, 1.02 |
| Any fetal loss (early or late) | ||||||
| None | 482 | 67.0 | 2,388 | 67.4 | 1.00 | reference |
| 1+ | 237 | 33.0 | 1,154 | 32.6 | 0.99 | 0.84, 1.18 |
| Number of prior fetal losses (<20 weeks)c | ||||||
| None | 500 | 69.5 | 2,472 | 69.8 | 1.00 | reference |
| 1+ | 219 | 30.5 | 1,069 | 30.2 | 0.99 | 0.83, 1.18 |
| Number of prior fetal losses (≥20 weeks)c,d | ||||||
| None | 698 | 97.1 | 3,429 | 97.1 | 1.00 | reference |
| 1+ | 21 | 2.9 | 104 | 2.9 | 1.09 | 0.67, 1.77 |
aAdjusted for maternal age and birth year
bp for trend ****P0.0007
cRestricted to 839 cases and 4,015 control whose mothers had a prior pregnancy
dAdjusted for maternal age, birth year, and paternal age