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Table 1 Basic characteristics of the study population in relation to asthma at any time among offspring

From: Parental smoking and cessation during pregnancy and the risk of childhood asthma

  Asthma* No asthma* p-value**
  n = 2641 (6.7 %) n = 36 665 (93.3 %)  
Primipara 1 039 (39.3) 15 131 (41.3) 0.114
Maternal    
Asthma 116 (4.4) 876 (2.4) <0.001
GDMa 143 (5.4) 2 314 (6.3) 0.066
Hypertension 76 (2.9) 725 (2.0) 0.002
Preeclampsia 115 (4.4) 1 438 (3.9) 0.217
ARTb 183 (6.9) 1736 (4.7) <0.001
Maternal age, years 28.7 (5.3) 29 (5.5) 0.313
<25 780 (29.5) 9 944 (27.1)  
26-35 1 581 (59.9) 22 049 (60.1)  
>35 280 (10.6) 4672 (12.7) 0.001
Mean prepregnancy BMIc, kg/m2 23.4 (4.5) 23.2 (4.3) 0.020
Mean number of previous pregnancies 1.5 (1.6) 1.4 (1.6) 0.08
Mean number of previous deliveries 1.1 (1.2) 1.0 (1.3) 0.57
Marital status    
not married 900 (34.1) 13 238 (36.1)  
married 1 741 (65.9) 23 427 (63.9) 0.036
Mode of delivery    
Vaginal 2 040 (77.2) 29 925 (81.6)  
Cesarean section 601 (22.8) 6 740 (18.4) <0.001
Single 2 500 (94.7) 35 340 (96.4)  
Twins 133 (5.0) 1 258 (3.4)  
Triplets 8 (0.3) 67 (0.2) <0.001
Premature delivery 380 (14.4) 2 594 (7.1) <0.001
Boy 1 602 (60.7) 18 241 (50.2) <0.001
Mean gestational age, w 38.4 (3.2) 39.2 (2.1) <0.001
Apgar score 5 min <7 70 (2.7) 663 (1.8) 0.002
Chorioamnionitisd 48 (1.8) 414 (1.1) 0.002
Mean follow-up time of children, years* 4.2 (3.6) 9.3 (5.3) <0.001
  1. *Values are mean (±2 SD) or N (%)
  2. ** p-value obtained in univariate model
  3. aGestational diabetes mellitus
  4. bART (assisted reprodution technology), including IVF (in-vitro fertilization), ICSI (intracytoplasmic sperm injection), insemination and ovulation induction by clomiphene and other medicines
  5. cData missing in 1984 (4.5 %) cases
  6. dData missing in 7 (0 %) cases