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Table 1 Characteristics of the mothers and children and their associations with childhood asthma in the case - control study

From: The effect of breastfeeding on the risk of asthma in high-risk children: a case-control study in Shanghai, China

Characteristics Case (n = 634) Control (n = 864) P-value OR 95% CI
Maternal educational level (years) < 0.0001   
  ≤ 9 37 (5.8) 161 (18.6)   0.2 0.2–0.4
 10–12 85 (13.4) 147 (17.0)   0.6 0.5–0.8
 13–16 406 (64.0) 434 (40.2)   ref ref
  ≥ 17 51 (8.0) 42 (4.7)   1.3 0.8–2.0
 Unknown 55 (8.7) 80 (9.3)   0.7 0.5–1.1
Maternal antibiotic use in pregnancy*   0.002   
 No 589 (92.9) 834 (96.5)   ref ref
 Yes 45 (7.1) 30 (3.5)   2.1 1.3–3.4
Maternal age at delivery (years) 28.5 (3.6) 27.7 (3.8) 0.0004 1.1 1.0–1.1
Gestational weeks at birth 38.8 (1.4) 38.9 (1.4) 0.1 0.9 0.9–1.0
Birth weight (g) 3305.6 (480.9) 3283.9 (500.4) 0.1 1.0 1.0–1.0
Delivery modes    0.02   
 Vaginal delivery 237 (37.4) 376 (43.5)   ref ref
 Caesarean delivery 397 (62.6) 488 (56.5)   1.3 1.0–1.6
Exclusive breastfeeding within the first 6 months of life   0.5   
 No 303 (47.8) 399 (46.2)   ref ref
 Yes 331 (52.2) 465 (53.8)   0.9 0.8–1.2
Child age (years) 5.7 (2.0) 6.3 (2.2) < 0.0001 0.8 0.8–0.9
Child gender    0.002   
 Female 252 (39.8) 414 (47.9)   ref ref
 Male 382 (60.2) 450 (52.1)   1.4 1.1–1.7
Child ethnicity 0.7   
 Han 612 (96.5) 837 (96.8)   ref ref
 Other 16 (2.5) 22 (2.6)   1.0 0.5–1.9
 Unknown 6 (1.0) 5 (0.6)   1.6 0.5–5.4
Family history of allergic disorders < 0.0001   
 No 289 (45.6) 679 (78.6)   ref ref
 Yes 334 (52.7) 173 (20.0)   4.5 3.6–5.7
 Unknown 14 (1.7) 12 (1.4)   2.2 0.9–4.9
  1. N (%) was used for maternal educational level, mother use of antibiotics in pregnancy, maternal age at delivery, delivery modes of children, exclusive breastfeeding within the first 6 months of life, child gender, child ethnicity, and family history of allergic disorders
  2. Means (SD) was used for maternal age at delivery, gestational age at birth (weeks), birth weight, and child age
  3. *Maternal use of antibiotics in pregnancy in our study excluded antibiotic use during labor or delivery
  4. OR: odds ratios