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Table 3 Birth year adjusted analyses of maternal reproductive characteristics, pregnancy history, and labor and delivery variables and childhood leukemia.

From: Parental and infant characteristics and childhood leukemia in Minnesota

  Sub-cohort ALL AML
  No. (%) No. (%) HR 95% CI No. (%) HR 95% CI
Plurality        
   1 8526 (97) 547 (98) ref. 86 (99) ND**
   ≥2 224 (3) 12 (2) 0.82 0.46–1.48 1 (1)   
   missing 1 (0) 1 (0)    0 (0)   
Previous live births        
   0 3449 (40) 202 (37) ref. 29 (33) ref.  
   1–2 4251 (49) 286 (52) 1.15 0.95–1.38 49 (56) 1.39 0.87–2.20
   ≥3 903 (11) 61 (11) 1.14 0.85–1.54 9 (10) 1.20 0.56–2.54
   missing 147 (2) 11 (2)    0 (0)   
Prior fetal loss        
   any 1866 (22) 134 (25) 1.14 0.94–1.41 19 (22) 1.00 0.59–1.68
   none 6711 (78) 407 (75) ref. 68 (78)   ref.
   missing 173 (3) 19 (3)    0 (0)   
Last fetal death interval        
   no fetal deaths 6564 (80) 404 (77) ref. 67 (82)   ref.
   <3 years 891 (11) 73 (14) 1.30 1.00–1.69 8 (10) 0.92 0.44–1.93
   ≥3 years 722 (9) 51 (10) 1.13 0.83–1.53 7 (8) 0.96 0.44–2.11
   missing 573 (7) 32 (6)    5 (6)   
Last live birth interval        
   no live births 3449 (40) 202 (37) ref. 29 (35) ref.  
   <3 years 3333 (39) 200 (36) 1.02 0.84–1.25 34 (40) 1.22 0.74–2.02
   ≥3 years 1786 (21) 148 (27) 1.40 1.12–1.75 21 (25) 1.40 0.79–2.47
   missing 182 (2) 10 (2)    3 (3)   
Maternal diabetes*        
   any 110 (3) 8 (3) 1.00 0.48–2.08 0 (0)   ND
   none 3194 (97) 229 (97) ref. 33 (100)   
   missing 215 (6) 9 (4)      
Gestational anemia        
   yes 80 (2) 8 (3) 1.52 0.72–3.19 1 (2)   ND
   no 4612 (98) 305 (97) ref. 42 (98)   
   missing 291 (6) 23 (7)    4 (9)   
Maternal hypertension        
   any 337 (4) 28 (6) 1.32 0.88–1.96 5 (6) 1.40 0.56–3.49
   none 7678 (96) 481 (94) ref. 76 (94)   ref.
   missing 735 (8) 51 (9)    6 (7)   
Intrauterine procedures        
   yes 203 (2) 13 (2) 1.01 0.57–1.78 2 (2) 0.97 0.24–4.00
   no 8181 (98) 515 (92) ref. 81 (98)   ref.
   missing 366 (4) 32 (6)    4 (5)   
Maternal weight gain +        
   < 30 lbs 2323 (60) 148 (56) ref. 12 (36)   ref.
   ≥ 30 lbs 1526 (40) 115 (44) 1.17 0.91–1.52 21 (64) 2.59 1.27–5.31
   missing 1134 (23) 73 (22)    14 (30)   
Prenatal care index        
   less than adequate 2300 (33) 146 (31) 0.95 0.77–1.16 16 (22) 0.57 0.33–1.00
   adequate 4747 (67) 323 (69) ref. 57 (78)   ref.
   missing 1151 (14) 72 (13)    11 (13)   
Induction of labor        
   yes 1432 (27) 92 (27) 0.97 0.75–1.24 18 (39) 1.67 0.91–3.04
   no 3878 (73) 244 (73) ref. 28 (61)   ref.
   missing 225 (4) 19 (5)    4 (8)   
Type of delivery        
   vaginal 6952 82) 432 (82) ref. 73 (86)   ref.
   caesarean section 1485 (18) 98 (18) 1.03 0.82–1.30 12 (14) 0.75 0.41–1.39
   missing 313 (4) 30 (5)    2 (2)   
  1. *collected 1992–2004.
  2. +collected 1989–2004.
  3. collected 1980–2004.
  4. collected 1976–1979, 1989–2004.
  5. **ND = not determined