Univariable analyses: factors associated with repeated (2+) and single (1) admissions by anomaly/rare disease subgroup
| 2+ admissions | 1 admission | |||||
| Unadjusted OR† | Unadjusted OR† | |||||
| Factors | All | Isolated | Multiple | All | Isolated | Multiple |
| Townsend quintile | ||||||
| 1 | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) |
| 2 | 1.03 (0.93 to 1.14) | 1.04 (0.92 to 1.18) | 1.06 (0.88 to 1.28) | 0.93 (0.83 to 1.05) | 0.88 (0.77 to 1.01) | 1.09 (0.87 to 1.37) |
| 3 | 1.01 (0.92 to 1.12) | 1.06 (0.93 to 1.20) | 0.93 (0.78 to 1.10) | 0.90 (0.81 to 1.01) | 0.88 (0.77 to 1.01) | 0.92 (0.74 to 1.14) |
| 4 | 1.24 (1.13 to 1.37) | 1.23 (1.08 to 1.39) | 1.24 (1.04 to 1.47) | 1.04 (0.93 to 1.16) | 1.02 (0.89 to 1.16) | 1.08 (0.87 to 1.34) |
| 5 | 1.31 (1.19 to 1.43) | 1.32 (1.18 to 1.48) | 1.28 (1.08 to 1.51) | 1.07 (0.96 to 1.18) | 1.02 (0.90 to 1.15) | 1.17 (0.96 to 1.44) |
| Maternal ethnicity | ||||||
| White | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) |
| Other | 1.11 (0.94 to 1.32) | 1.10 (0.88 to 1.38) | 1.06 (0.82 to 1.39) | 1.26 (1.05 to 1.52) | 1.34 (1.06 to 1.69) | 1.13 (0.82 to 1.56) |
| Maternal age at delivery, years | ||||||
| ≤24 | 1.19 (1.10 to 1.28) | 1.16 (1.05 to 1.27) | 1.23 (1.07 to 1.41) | 0.99 (0.91 to 1.09) | 0.97 (0.87 to 1.07) | 1.05 (0.88 to 1.25) |
| 25–29 | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) |
| 30–34 | 0.92 (0.85 to 1.00) | 0.89 (0.81 to 0.98) | 0.94 (0.81 to 1.09) | 0.92 (0.84 to 1.01) | 0.93 (0.83 to 1.04) | 0.90 (0.75 to 1.07) |
| ≥35 | 0.53 (0.49 to 0.58) | 0.50 (0.45 to 0.56) | 0.55 (0.48 to 0.64) | 0.55 (0.50 to 0.61) | 0.54 (0.48 to 0.61) | 0.58 (0.48 to 0.69) |
| Parity | ||||||
| Nulliparous | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) |
| ≥1 | 0.73 (0.69 to 0.77) | 0.73 (0.68 to 0.79) | 0.76 (0.68 to 0.84) | 0.78 (0.73 to 0.84) | 0.78 (0.72 to 0.85) | 0.80 (0.71 to 0.91) |
| Multiple fetus | ||||||
| Yes | 1.66 (1.39 to 1.98) | 1.92 (1.53 to 2.39) | 1.20 (0.89 to 1.60) | 1.23 (1.00 to 1.52) | 1.43 (1.11 to 1.84) | 0.87 (0.60 to 1.27) |
| No | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) |
| Maternal smoking | ||||||
| Smoker | 1.30 (1.19 to 1.41) | 1.32 (1.19 to 1.48) | 1.24 (1.09 to 1.43) | 1.09 (0.99 to 1.20) | 1.06 (0.94 to 1.20) | 1.14 (0.96 to 1.34) |
| Non/ex-smoker | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) |
| Anomalies in previous pregnancies | ||||||
| Yes | 1.00 (0.89 to 1.11) | 1.04 (0.91 to 1.20) | 0.81 (0.67 to 0.99) | 0.98 (0.86 to 1.11) | 1.00 (0.86 to 1.16) | 0.90 (0.70 to 1.14) |
| No | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) |
| Infant sex* | ||||||
| Male | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) |
| Female | 0.95 (0.90 to 1.00) | 0.94 (0.87 to 1.01) | 0.88 (0.79 to 0.97) | 1.01 (0.95 to 1.08) | 1.07 (0.99 to 1.16) | 0.86 (0.76 to 0.97) |
| Gestational age,* weeks | ||||||
| <37 | 2.95 (2.70 to 3.23) | 3.25 (2.89 to 3.64) | 2.15 (1.87 to 2.49) | 1.79 (1.61 to 1.98) | 1.91 (1.67 to 2.18) | 1.48 (1.24 to 1.77) |
| ≥37 | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) | 1 (reference) |
*Variable identified for inclusion a priori.
†For ‘All’ anomaly subgroup, adjusted variables include maternal age at delivery, maternal smoking, infant sex and gestational age; for ‘isolate’ anomaly subgroup, adjusted variables include maternal smoking, infant sex and gestation age; for ‘multiple’ anomaly subgroup, adjusted variables include maternal age at delivery, infant sex and gestational age. Statistical significance at p<0.05.