From: Revisiting the association between maternal and offspring preterm birth using a sibling design
Maternal gestational age | Infant’s preterm birth cases/No of births | Preterm birth rate, % | URR | 95% CI | ARR c | 95% CI |
---|---|---|---|---|---|---|
Population cohorta (N = 79,198) | ||||||
 Not Preterm | 4588/75,427 | 6.08 | 1.00 | Reference | 1.00 | Reference |
 Preterm (24–36 weeks) | 325/3771 | 8.62 | 1.42 | 1.27, 1.58 | 1.39 | 1.25, 1.54 |
 Very Preterm (24–31 weeks) | 35/326 | 10.74 | 1.77 | 1.28, 2.42 | 1.76 | 1.29, 2.41 |
 Moderately Preterm (32–36 weeks) | 290/3445 | 8.43 | 1.38 | 1.24, 1.55 | 1.35 | 1.21, 1.51 |
Sibling subcohortb (N = 2499) | ||||||
 Not Preterm | 143/1430 | 10.00 | 1.00 | Reference | 1.00 | Reference |
 Preterm (24–36 weeks) | 109/1069 | 10.20 | 1.02 | 0.77, 1.36 | 1.02 | 0.77, 1.34 |
 Very Preterm (24–31 weeks) | 7/80 | 8.75 | 0.88 | 0.39, 1.96 | 0.88 | 0.38, 2.02 |
 Moderately Preterm (32–36 weeks) | 102/989 | 10.31 | 1.03 | 0.77, 1.38 | 1.03 | 0.78, 1.36 |