Skip to main content

Advertisement

Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

Table 1 Age-standardized characteristics by calendar-year-adjusted PM2.5 quintiles in premenopausal (n = 1624) and postmenopausal (n = 1634) participants

From: Residential particulate matter and distance to roadways in relation to mammographic density: results from the Nurses’ Health Studies

  Premenopausal women Postmenopausal women
Characteristica 1st quintile (n = 331) 5th quintile (n = 332) 1st quintile (n = 331) 5th quintile (n = 334)
Age at mammogramb 45.6 ± 4.2 45.6 ± 4.3 60.0 ± 7.4 59.7 ± 7.6
NHSII cohort (%) 76 78 19 24
BMI at mammogram (kg/m2) 25.1 ± 5.6 25.8 ± 5.5 26.1 ± 5.0 26.5 ± 5.6
Presence of biopsy-confirmed benign breast disease (%) 18.8 17.8 23.4 21.8
Current use of hormonal therapy (%) 2.7 2.3 52.2 47.3
Parity and age at first birth status (%)
 Nulliparous 16.3 16.5 9.8 9.8
 1–4 children before age 25 29.0 29.3 36.5 38.2
 1–4 children between age 25 and 30 33.8 34.4 31.9 29.5
 1–4 children after age 30 17.7 17.0 8.6 9.8
 5+ children 2.6 1.9 12.6 11.7
 Missing 0.6 0.9 0.5 1.0
Categories of BMI at age 18 (%)
  < 19.0 kg/m2 16.0 17.8 10.6 13.3
 19.0–24.9 kg/m2 72.2 70.7 75.6 72.9
 25–29.9 kg/m2 7.4 8.5 9.4 8.1
 30+ kg/m2 1.9 1.7 0.9 1.9
 Missing 2.5 1.3 3.5 3.8
Family history of breast cancer (%) 10.7 8.5 13.0 11.0
Age at menarche (years) 12.4 ± 1.4 12.4 ± 1.4 12.4 ± 1.3 12.6 ± 1.5
Lactation among parous women (%)
 Never breastfed 15.0 21.9 35.8 41.5
 Yes‚ breastfed > 1 month 82.5 75.1 62.8 57.0
 Missing 2.5 3.1 1.5 1.3
Oral contraceptive use (%)
 Not on oral contraceptives 94.4 93.4
 Current < 5 years 2.6 1.5
 Current 5 + years 2.7 4.9
 Missing 0.3 0.3
Alcohol consumption (g/day) 5.3 ± 8.4 3.8 ± 6.3 5.6 ± 9.1 4.8 ± 8.1
Physical activity (MET hours/week) 22.2 ± 29.6 17.5 ± 19.2 17.6 ± 17.3 19.4 ± 26.3
White (%) 99.4 97.5 98.6 97.7
Region of residence (%)
 Northeast 27.8 27.4 28.0 33.4
 Midwest 13.8 40.5 6.5 34.8
 West 39.4 16.5 33.8 20.6
 South 18.9 15.6 31.7 11.2
Distance from residential address to A1–A3 roadways (meters) 313.8 ± 185.9 231.1 ± 169.6 299.0 ± 187.5 220.2 ± 168.1
  1. PM 2.5 particulate matter less than 2.5 μm in diameter, NHSII Nurses’ Health Study II, BMI body mass index, MET metabolic equivalent
  2. aValues are mean ± SD or percentages and are standardized to the age distribution of the study population. Values of polytomous variables may not sum to 100% due to rounding
  3. bValue is not age adjusted