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Table 3 Breast cancer odds ratio (ORs) in relation to participant’s perinatal exposures, excluding in situ cases

From: Perinatal and postnatal exposures and risk of young-onset breast cancer

Characteristics Controls (n = 1467) Cases (n = 1250) OR (95% CI) OR (95% CI)
Preeclampsia/eclampsia/toxemia n (%) n (%)   
 No 990 (98.5) 867 (97.6) 1.00 1.00
 Yes 15 (1.5) 21 (2.4) 2.87 (1.08–7.59)¥ 4.03 (1.29–12.6)
Gestational hypertension§
 No 958 (97.5) 818 (97.7) 1.00 1.00
 Yes 25 (2.5) 19 (2.3) 0.91 (0.46–1.80) 1.00 (0.49–2.04)
Any hypertensive disorder
 No 984 (96.1) 867 (98.6) 1.00 1.00
 Yes 40 (3.9) 40 (4.4) 1.32 (0.75–2.32)¥ 1.58 (0.85–2.92)
Maternal smoking
 No 787 (70.5) 692 (70.3) 1.00  
 Yes 329 (29.5) 292 (29.7) 1.13 (0.75–1.70)*  
Low birth weight
 Birth weight > 5.5 pounds 1033 (93.3) 907 (92.3) 1.00 1.00
 Birth weight ≤5.5 pounds 74 (6.7) 76 (7.7) 1.17 (0.78–1.74) 1.14 (0.71–1.81)Ŧ
High birth weight
 Birth weight < 8.8 pounds 741 (91.8) 642 (89.4) 1.00 1.00
 Birth weight ≥ 8.8 pounds 66 (8.2) 76 (10.6) 1.67 (1.10–2.54) 1.52 (0.96–2.40)Ŧ
Breastfed
 No 664 (60.2) 611 (62.7) 1.00  
 Yes 438 (39.8) 364 (37.3) 0.80 (0.60–1.07)  
Soy-fed (formula made from soy)
 No 847 (95.6) 743 (95.5) 1.00  
 Yes 39 (4.4) 35 (4.5) 0.92 (0.56–1.52)  
DES exposure during pregnancy
 No 872 (96.8) 776 (97.1) 1.00  
 Yes 29 (3.2) 23 (2.9) 0.85 (0.44–1.65)  
Short gestational length at birth
 Born ≥ 38 weeks 474 (87.8) 412 (84.6) 1.00 1.00
 Born < 38 weeks 66 (12.2) 75 (15.4) 1.38 (0.90–2.11) 1.28 (0.81–2.02)Ŧ
  1. Counts including only participants with complete information on exposure of interest
  2. ¥Adjusted for whether or not the participant was their mother’s first baby and for maternal smoking in that pregnancy
  3. §Without preeclampsia/eclampsia
  4. *Adjusted by birth order
  5. Adjusted for whether or not the participant was their mother’s first baby, for maternal smoking in that pregnancy and excluding women who themselves had a preeclamptic pregnancy
  6. ŦAdjusted for mother’s preeclampsia and smoking during the participant’s gestation