Table 6

Association between maternal history of miscarriages and childhood asthma at 7 years

Study populationExposureExposure groupNN cases (%)Unadjusted
RR (95% CI)
Adjusted*
RR (95% CI)
Register-based cohortNumber of miscarriages within the first 12 gestational weeksNone374 86615 628 (4.2)11
173 3233256 (4.4)1.07 (1.03 to 1.11)1.07 (1.03 to 1.11)
218 415902 (4.9)1.17 (1.10 to 1.26)1.18 (1.10 to 1.26)
3 or more7798403 (5.2)1.24 (1.12 to 1.37)1.24 (1.12 to 1.37)
Number of miscarriages between 12 and 23 gestational weeksNone448 19818 979 (4.2)11
111 086546 (4.9)1.16 (1.07 to 1.27)1.21 (1.11 to 1.32)
2127353 (4.2)0.98 (0.75 to 1.29)1.04 (0.79 to 1.36)
3 or more41818 (4.3)1.02 (0.65 to 1.60)1.04 (0.66 to 1.65)
MoBaNumber of miscarriages within the first 22 gestational weeksNone60 9822564 (4.2)11
111 364499 (4.4)1.04 (0.95 to 1.15)1.06 (0.96 to 1.16)
22555123 (4.8)1.14 (0.96 to 1.37)1.18 (0.98 to 1.41)
3 or more89643 (4.8)1.14 (0.85 to 1.53)1.14 (0.85 to 1.53)
  • *The analysis of the register-based cohort was adjusted for maternal age, parity and maternal current asthma. The analysis of MoBa was adjusted for maternal age, parity, education, smoking during pregnancy, prepregnancy BMI and maternal current asthma.

  • BMI, body mass index; MoBa, Norwegian Mother and Child Cohort Study; RR, relative risk.