Risk of incident asthma in children in association with the level of control and severity of maternal asthma during pregnancy
| Adjusted OR (95% CI) | |
| Control and severity of maternal asthma during pregnancy | |
| Mild controlled | Reference# |
| Mild uncontrolled | 1.04 (0.87–1.25) |
| Moderate-to-severe controlled | 1.43 (0.54–3.74) |
| Moderate-to-severe uncontrolled | 1.27 (1.06–1.52) |
| Child | |
| Male sex | 1.50 (1.18–1.91) |
| Atopic dermatitis | 2.05 (1.30–3.24) |
| Antibiotic prescription between birth and index date or within first 6 months of life | 1.71 (1.33–2.20) |
| Breastfeeding | |
| <6 months | 0.60 (0.44–0.80) |
| ≥6 months | 0.75 (0.54–1.04) |
| Unknown duration | 0.67 (0.33–1.38) |
| No breastfeeding | Reference |
| Administration of O2 to newborn | |
| >24 h in hospital after birth | 1.95 (1.26–3.03) |
| Unknown duration | 1.33 (0.83–2.11) |
| No O2 administration | Reference |
| At least one diagnosis of a bronchopulmonary disease¶ prior to index date | |
| No | Reference |
| Yes | 2.96 (2.28–3.83) |
| Yes, but at unknown age | 3.25 (2.11–5.01) |
| Maternal socio-demographics | |
| Mother receiving social welfare | 1.88 (1.39–2.53) |
| Child always living with mother prior to index date | 2.65 (1.14–6.17) |
| Pregnancy | |
| Number of antibiotic prescriptions filed+ | 1.13 (1.01–1.27) |
| Maternal health | |
| Maternal atopy§ | 0.71 (0.51–0.98) |
| Siblings' health | |
| Paternal history of asthma | 1.46 (1.00–2.13) |
| History of asthma in siblings | 1.45 (1.09–1.94) |
| No history of asthma in siblings | Reference |
| No siblings | 0.93 (0.69–1.26) |
| Environment | |
| Presence of wood-burning fireplace in home prior to index date | 0.57 (0.40–0.79) |
| Day-care attendance prior to index date | 0.76 (0.60–0.98) |
| Presence of pets at home (>2 months) prior to index date | 0.63 (0.50–0.81) |
Final multivariate analysis: reduced model combining first- and second-stage variables. Adjusted odds ratios (ORs) displayed are adjusted for all other variables presented in the table. #: reference category for variables composed of >2 categories; ¶: wheezing, bronchiolitis, bronchitis or pneumonia; +: each additional prescription; §: >1 marker for maternal atopy: allergic rhinitis, atopic dermatitis, hay fever or other allergies.