Childhood body size and pubertal timing in relation to adult mammographic density phenotype

Breast Cancer Research

Table 1 Characteristics of the study population (subjects with mammographic density data participating in the Generations Study)

	Participants
Characteristic	Adjusted mean percentage density^a	Number	Percentage of subjects
Age at mammogram, years
47–54	25.5	303	27.4
55–59	21.3	344	31.1
60–64	18.0	279	25.2
65–73	16.6	179	16.2
Interval between mammogram and baseline questionnaire
≥3 years prior	21.6	47	4.3
2–2.9 years prior	24.3	61	5.5
1–1.9 years prior	24.0	182	16.5
Within 1 year	21.1	554	50.1
1–1.9 years later	19.3	127	11.5
2–2.9 years later	22.0	59	5.3
≥3 years later	17.2	75	6.8
BMI at baseline questionnaire, kg/m ²
<20	33.0	39	3.5
20–24	25.6	525	47.5
25–29	15.7	378	34.2
≥30	12.1	163	14.8
Menopausal status at mammogram
Postmenopausal	20.5	885	80.1
Premenopausal	24.5	126	11.4
Status not known	23.2	94	8.5
Parity
Nulliparous	24.5	113	10.2
Parous	20.9	992	89.8
Age at first birth, years
<25	19.9	428	38.7
25–29	21.4	414	37.5
≥30	22.4	150	13.6
Number of births
1	19.7	100	9.0
2	21.1	583	52.8
≥3	21.0	309	28.0
Postmenopausal hormone replacement at time of mammogram
Never	21.0	839	75.9
Former	21.0	199	18.0
Current	25.7	67	6.1
Total study population	21.3	1105	100.0

^aMean percentage mammographic density (back-transformed to ordinary scale) for average body mass index (BMI) 25 kg/m² and age 58 years at mammogram for all variables, except category of age at mammogram (at BMI 25 kg/m² only) and category of BMI (at age 58 years only)

ISSN: 1465-542X