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Table 2 RR for asthma hospitalization in childhood according to birth weight, gestational age, and fetal growth

From: Birth weight, gestational age, fetal growth and childhood asthma hospitalization

Fetal development variables Cases Cumulative incidence (%) Crude RR Adjusted RR* (95% CI)
Birth weight     
  <1000 g 542 8.35 3.03 2.33 (2.14-2.53)
  1000-1499 g 897 5.93 2.21 1.81 (1.68-1.95)
  1500-1999 g 1,423 4.51 1.69 1.48 (1.40-1.57)
  2000-2499 g 3,823 3.67 1.38 1.33 (1.28-1.38)
  2500-2999 g 14,992 2.98 1.12 1.15 (1.12-1.17)
  3000-3499 g 41,716 2.73 1.02 1.05 (1.04-1.07)
  3500-3999 g 44,451 2.67 1 1 (ref)
  4000-4499 g 19,371 2.73 1.02 0.99 (0.97-1.01)
  4500-4999 g 4,037 2.89 1.08 1.03 (0.99-1.06)
  ≥5000 g 531 2.87 1.08 1.01 (0.92-1.11)
Birth weight per 1000-g decrease - - 1.18 1.17 (1.15-1.18)
Gestational age     
  22-28 weeks 737 8.07 2.89 2.26 (2.10-2.43)
  29-32 weeks 1,416 5.16 1.88 1.63 (1.54-1.73)
  33-36 weeks 6,471 3.50 1.28 1.26 (1.22-1.29)
  37-38 weeks 23,062 2.98 1.09 1.10 (1.09-1.12)
  39-41 weeks 91,055 2.73 1 1 (ref)
  42-45 weeks 9,042 2.37 0.86 0.98 (0.95-1.00)
GA per reduced week - - 1.07 1.05 (1.04-1.06)
Fetal growth     
  SGA 4,878 3.38 1.23 1.20 (1.16-1.24)
  AGA 121,741 2.76 1 1 (ref)
  LGA 5,164 3.18 1.15 1.05 (1.02-1.09)
Z-score per decreased of SD - - 1.00 1.03 (1.02-1.04)
  1. *Adjusted for country of residence, maternal age at delivery, maternal social status, parity, mode of delivery, sex of the child, calendar year of birth and family history of asthma.