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Table 6 Breast cancer odds ratio (ORs) in relation to participant’s in utero exposures by ER status, with counts including only participants with complete information on exposure of interest

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

Characteristics ER+ cases (1161 case subjects, 1321 control subjects) ER− cases (290 case subjects, 328 control subjects)
Controls (n = 1321) Cases (n = 1161) OR (95% CI) OR (95% CI) Controls (n = 328) Cases (n = 290) OR (95% CI) OR (95% CI)
Preeclampsia/eclampsia/toxemia
 No 949 (98.3) 840 (98.4) 1.00 1.00 200 (98.5) 174 (95.6) 1.00 1.00
 Yes 16 (1.7) 14 (1.6) 1.23 (0.48–3.16)¥ 1.41 (0.50–3.97) 3 (1.5) 8 (4.4) ǂ ǂ
Gestational hypertension§
 No 913 (97.5) 794 (98.0) 1.00 1.00 196 (97.5) 161 (97.0) 1.00 1.00
 Yes 23 (2.5) 16 (2.0) 0.75 (0.35–1.60)¥ 0.87 (0.38–1.97) 5 (2.5) 5 (3.0) 1.09 (0.31–3.79)¥ 1.37 (0.36–5.19)
Any hypertensive disorder
 No 944 (96.0) 843 (95.6) 1.00 1.00 200 (96.2) 173 (93.0) 1.00 1.00
 Yes 39 (4.0) 30 (3.4) 0.86 (0.46–1.59)¥ 0.98 (0.50–1.90) 8 (3.9) 13 (7.0) 2.83 (0.85–9.39)¥ 5.61 (1.19–26.4)
Maternal smoking
 No 757 (70.4) 665 (70.0) 1.00   166 (71.9) 145 (70.0) 1.00  
 Yes 319 (29.6) 285 (30.0) 1.18 (0.77–1.82)*   65 (28.1) 62 (30.0) 1.23 (0.54–2.80)*  
Low birth weight
 Birth weight > 5.5 pounds 992 (93.5) 867 (92.3) 1.00 1.00 218 (91.9) 199 (91.7) 1.00 1.00
 Birth weight ≤ 5.5 pounds 69 (6.5) 72 (7.7) 1.23 (0.82–1.85) 1.22 (0.76–1.96)Ŧ 19 (8.0) 18 (8.3) 0.95 (0.46–1.98) 0.85 (0.35–2.05)Ŧ
High birth weight
 Birth weight < 8.8 pounds 712 (92.6) 614 (90.2) 1.00 1.00 162 (92.1) 150 (91.5) 1.00 1.00
 Birth weight ≥ 8.8 pounds 57 (7.4) 67 (9.8) 1.68 (1.07–2.62) 1.53 (0.95–2.48)Ŧ 14 (7.9) 14 (8.5) 1.34 (0.55–3.28) 1.35 (0.48–3.80)Ŧ
Breastfed
 No 640 (60.2) 582 (61.8) 1.00   130 (57.5) 134 (65.7) 1.00  
 Yes 424 (39.9) 360 (38.2) 0.83 (0.61–1.13)   96 (42.5) 70 (34.3) 0.53 (0.29–0.99)  
Soy-fed (formula made from soy)
 No 827 (96.3) 722 (95.5) 1.00   181 (94.3) 163 (95.3) 1.00  
 Yes 32 (3.7) 34 (4.5) 1.19 (0.70–2.01)   11 (5.7) 8 (4.7) 0.70 (0.27–1.84)  
DES exposure during pregnancy
 No 860 (96.9) 770 (97.2) 1.00   171 (98.3) 152 (98.1) 1.00  
 Yes 28 (3.2) 22 (2.8) 0.85 (0.44–1.65)   3 (1.7) 3 (1.9) 1.00 (0.14–7.10)  
Short gestational length at birth
 Born ≥ 38 weeks 460 (87.3) 400 (84.8) 1.00 1.00 93 (91.2) 82 (85.4) 1.00 1.00
 Born < 38 weeks 67 (12.7) 72 (15.2) 1.25 (0.82–1.92) 1.19 (0.76–1.85)Ŧ 9 (8.8) 14 (48.6) 2.39 (0.73–7.79) 2.11 (0.52–8.59)Ŧ
  1. ¥Adjusted for whether or not the participant was their mother’s first baby and for maternal smoking in that pregnancy
  2. §Without preeclampsia/eclampsia
  3. *Adjusted by birth order
  4. ǂNot enough participants in this category to generate an estimate
  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