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Table 2 Maternal background characteristics by socioeconomic status (SES)

From: Maternal socioeconomic status and the risk of asthma among offspring

  Total n(%) Upper white-collar worker n(%) Lower white-collar worker n(%) Blue-collar worker n(%) Other n(%) Missing n(%) p value
Maternal age, years        
 <20 1315(3.3) 10(0.2) 125(0.8) 196(2.4) 788(8.5) 196(8.4)  
 20-29 20 979(52.3) 2087(36.4) 7426(50.3) 4629(57.8) 5658(60.9) 1179(50.7)  
 30-39 16 559(41.3) 3406(59.4) 6728(45.6) 2942(36.8) 2617(28.2) 866(37.3)  
 ≥40 1265(3.2) 231(4.0) 484(3.3) 238(3.0) 229(2.5) 83(3.6) <0.001
Asthma 1129(2.8) 136(2.4) 438(3.0) 172(2.1) 285(3.1) 98(4.2) <0.001
Hypertension 790(2.0) 94(1.6) 325(2.2) 158(2.0) 169(1.8) 44(1.9) 0.074
ART1 1656(4.1) 327(5.7) 717(4.9) 304(3.8) 244(2.6) 64(2.8) <0.001
Infertility (own opinion) 2290(5.7) 489(8.5) 971(6.6) 428(5.3) 316(3.4) 86(3.7) <0.001
Pre-pregnancy BMI2, kg/m2        
 <25 27 377(71.3) 4232(76.7) 10 140(71.2) 5180(67.4) 6439(72.1) 1386(69.2)  
 25-29.9 7 585(19.8) 975(17.7) 2871(20.2) 1690(22.0) 1659(22.0) 390(19.5)  
 ≥30 3 410(8.9) 310(5.6) 1227(8.6) 815(10.6) 831(9.3) 227(11.3) <0.001
Marital status        
Unmarried 4 212(10.5) 360(6.3) 1364(9.2) 1038(13.0) 1110(11.9) 340(14.6)  
Married or cohabiting 35 906(89.5) 5374(93.7) 13 399(90.8) 6967(87.0) 8182(88.1) 1984(85.4) <0.001
Mean number of deliveries3 1.0(1.3) 1.0(1.2) 1.0(1.1) 1.0(1.2) 1.3(1.6) 0.9(1.3) <0.001
Mean number of pregnancies3 1.4(1.6) 1.3(1.5) 1.4(1.4) 1.4(1.5) 1.7(2.0) 1.4(1.6) <0.001
Mean numbers of miscarriages3 0.2(0.6) 0.2(0.6) 0.2(0.5) 0.2(0.5) 0.2(0.6) 0.2(0.6) 0.004
Mean number of artificial abortions3 0.1(0.4) 0.1(0.3) 0.1(0.4) 0.2(0.5) 0.1(0.4) 0.2(0.4) 0.001
Surgically scarred urerus 3590(8.9) 513(8.9) 1325(9.0) 776(9.7) 831(8.9) 145(6.2) <0.001
Total 40 118(100) 5734(14.3) 14 763(36.8) 8005(20.0) 9292(23.2) 2324(5.8)  
  1. 1Assisted reproduction technology before index pregnancy including in vitro fertilization, intracytoplasmic sperm injection, insemination and ovulation induction by clomifene and other medizines.
  2. 2Body mass index, data missing in 1746 (4.4%) cases.
  3. 3Data are presented as mean (±SD).