Table 2

Univariable analyses: factors associated with repeated (2+) and single (1) admissions by anomaly/rare disease subgroup

2+ admissions1 admission
Unadjusted OR†Unadjusted OR†
FactorsAllIsolatedMultipleAllIsolatedMultiple
Townsend quintile
 11 (reference)1 (reference)1 (reference)1 (reference)1 (reference)1 (reference)
 21.03 (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)
 31.01 (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)
 41.24 (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)
 51.31 (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
 White1 (reference)1 (reference)1 (reference)1 (reference)1 (reference)1 (reference)
 Other1.11 (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
 ≤241.19 (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)
 25–291 (reference)1 (reference)1 (reference)1 (reference)1 (reference)1 (reference)
 30–340.92 (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)
 ≥350.53 (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
 Nulliparous1 (reference)1 (reference)1 (reference)1 (reference)1 (reference)1 (reference)
 ≥10.73 (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
 Yes1.66 (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)
 No1 (reference)1 (reference)1 (reference)1 (reference)1 (reference)1 (reference)
Maternal smoking
 Smoker1.30 (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-smoker1 (reference)1 (reference)1 (reference)1 (reference)1 (reference)1 (reference)
Anomalies in previous pregnancies
 Yes1.00 (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)
 No1 (reference)1 (reference)1 (reference)1 (reference)1 (reference)1 (reference)
Infant sex*
 Male1 (reference)1 (reference)1 (reference)1 (reference)1 (reference)1 (reference)
 Female0.95 (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
 <372.95 (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)
 ≥371 (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.