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Table 3 Association between maternal and offspring preterm birth type in the population cohort a, Manitoba, Canada, 1980–2016

From: Revisiting the association between maternal and offspring preterm birth using a sibling design

  

Infant’s PTB cases/No of births

PTB rate, %

(N = 78,922)

(N = 78,922)

(N = 74,196)

(N = 39,478)

Offspring outcome

Maternal PTB type

URR

95% CI

ARRb

95% CI

ARRc

95% CI

ARRd

95% CI

Any PTB

Not Preterm

4565/75,172

6.07

1.00

Reference

1.00

Reference

1.00

Reference

1.00

Reference

Spontaneous

195/2165

9.01

1.48

1.29, 1.70

1.47

1.28, 1.68

1.43

1.24, 1.65

1.28

1.03, 1.58

Provider-initiated

128/1585

8.08

1.33

1.12, 1.57

1.29

1.09, 1.52

1.23

1.02, 1.47

1.14

0.87, 1.48

Spontaneous PTB

Not Preterm

3164/75,172

4.21

1.00

Reference

1.00

Reference

1.00

Reference

1.00

Reference

Spontaneous

149/2165

6.88

1.64

1.40, 1.92

1.61

1.38, 1.89

1.57

1.32, 1.85

1.33

1.04, 1.71

Provider-initiated

93/1585

5.87

1.39

1.14, 1.70

1.36

1.11, 1.66

1.32

1.07, 1.64

1.09

0.78, 1.52

Provider-initiated PTB

Not Preterm

1401/75,172

1.86

1.00

Reference

1.00

Reference

1.00

Reference

1.00

Reference

Spontaneous

46/2165

2.12

1.14

0.85, 1.52

1.13

0.85, 1.52

1.11

0.82, 1.51

1.16

0.76, 1.77

Provider-initiated

35/1585

2.21

1.18

0.85, 1.65

1.13

0.81, 1.57

1.00

0.69–1.46

1.24

0.77, 1.99

  1. Abbreviations: PTB preterm birth, URR Unadjusted Relative Risk, ARR Adjusted Relative Risk, CI confidence intervals
  2. aAnalyzed with a log-binomial regression model. 276 children excluded due to missing information on maternal PTB type
  3. bAdjusted for whether mother moved or had a substance abuse diagnosis in year before birth of child, child’s birth year, mother’s age at birth of child, neighborhood location and SES at birth of child, child’s sex and child’s birth order
  4. cRestricted to births 2000–2016 with complete information on additional covariates. Adjusted for whether mother moved or had a substance abuse diagnosis in year before birth of child, child’s birth year, mother’s age at birth of child, neighborhood location and SES at birth of child, child’s sex, child’s birth order, mother’s smoking status during pregnancy, mother’s education, inadequate prenatal care, receipt of employment income assistance in the year before the birth of the child, and whether mother had a partner
  5. dRestricted to one randomly child per mother (1995–2016). Adjusted for whether mother moved or had a substance abuse diagnosis in year before birth of child, child’s birth year, mother’s age at birth of child, neighborhood location and SES at birth of child, child’s sex and child’s birth order