Table 1.
Crude relative risks for admission to hospital with asthma between 2 and 5 yrs of age
| Maternal/pregnancy/delivery factor | Infant asthma admissions/n | Crude relative risk RR (95% CI) |
|---|---|---|
| Maternal asthma admission* | 508/8326 | 2.10 (1.93–2.30) |
| Maternal age (yrs) | ||
| <20 | 381/10,210 | 1.25 (1.13–1.38) |
| 20–34 | 5518/185,315 | 1.0 (referent) |
| ≥35 | 1346/44,883 | 1.01 (0.95–1.07) |
| Parity | ||
| Nulliparous (first child) | 3018/100,115 | 1.01 (0.96–1.07) |
| Parity = 1 | 2473/81,462 | 1.02 (0.96–1.08) |
| Parity ≥ 2 | 1749/58,762 | 1.0 (referent) |
| Smoked during pregnancy | 1308/38,468 | 1.16 (1.09–1.23) |
| Urban area resident | 5146/164,667 | 1.13 (1.07–1.19) |
| Area socio-economic percentile | ||
| >80th (most advantaged) | 1360/49,008 | 0.87 (0.81–0.93) |
| >60th to 80th percentile | 1360/47,297 | 0.90 (0.84–0.96) |
| 40th to 60th percentile | 1568/48,914 | 1.0 (referent) |
| 20th to <40th percentile | 1441/47,770 | 0.94 (0.88–1.01) |
| <20th (most disadvantaged) | 1512/47,440 | 0.99 (0.93–1.07) |
| Any maternal diabetes | 434/13,107 | 1.01 (1.00–1.22) |
| Any maternal hypertension | 782/23,992 | 1.09 (1.02–1.17) |
| Season of conception | ||
| Autumn | 1796/58,445 | 1.09 (1.02–1.16) |
| Winter | 1980/60,943 | 1.15 (1.08–1.23) |
| Spring | 1745/59,908 | 1.03 (0.97–1.10) |
| Summer | 1724/61,175 | 1.0 (referent) |
| Antenatal admit UTI† | 123/2499 | 1.64 (1.38–1.96) |
| Rupture of membranes | ||
| Pre-term PROM‡ | 189/3453 | 1.85 (1.61–2.13) |
| Term PROM‡ | 559/17,402 | 1.09 (1.00–1.18) |
| No PROM‡ | 6497/219,656 | 1.0 (referent) |
| Gestational age (wks) | ||
| ≤31 | 126/1459 | 3.11 (2.62–3.68) |
| 32–33 | 88/1466 | 2.16 (1.76–2.65) |
| 34–36 | 364/9303 | 1.41 (1.27–1.57) |
| 37–39 | 3225/104,369 | 1.11 (1.06–1.17) |
| ≥40 | 3442/123,875 | 1.0 (referent) |
| Induction with prostaglandins | 812/27,708 | 0.97 (0.90–1.04) |
| Mode of delivery | ||
| Cesarean section | 1901/59,073 | 1.09 (1.04–1.15) |
| Instrumental | 783/25,864 | 1.03 (0.96–1.11) |
| Normal vaginal | 4560/155,533 | 1.0 (referent) |
| Male infant | 4661/124,114 | 1.69 (1.61–1.77) |
| Birthweight percentile | ||
| SGA (<10th percentile) | 805/24,118 | 1.12 (1.04–1.20) |
| 10th–90th | 5721/191,604 | 1.0 (referent) |
| LGA (>90th percentile) | 719/24,746 | 0.97 (0.90–1.05) |
| Respiratory distress syndrome | 193/3062 | 2.12 (1.85–2.44) |
| Transient tachypnea | 306/7271 | 1.41 (1.26–1.58) |
| Jaundice and/or phototherapy | 548/12,831 | 1.45 (1.33–1.58) |
| Neonatal bacterial sepsis | 57/957 | 1.99 (1.54–2.56) |
LGA, large-for-gestational-age’ PROM, pre-labor rupture of membranes; SGA, small-for-gestational-age.
*
Mother was admitted with asthma anytime between July 2000 and June 2009.
†
Urinary tract infection.
‡
Spontaneous pre-labor rupture of membranes.