Table 1.

Characteristics of the study population by tertiles of HDL-C (mmol/L)

HDL-C <1.39HDL-C 1.39–1.67HDL-C >1.67
Study characteristics(n = 66)a(n = 68)a(n = 65)aPb
Age, y31.0 (3.09)30.3 (3.01)30.9 (3.11)0.303
Education, total, y15.8 (3.17)16.4 (2.94)15.8 (3.03)0.400
Reproductive factorsc
 Age at menarche, y12.8 (1.32)13.3 (1.36)13.3 (1.40)0.072
 Menstrual cycle length, d28.5 (3.00)28.5 (3.56)27.7 (2.98)0.296
 Number of children, no.1.17 (1.14)0.69 (0.90)0.91 (1.30)0.052
Clinical parameters
 BMI, kg/m2d26.1 (4.21)24.0 (3.52)22.9 (2.63)<0.001
 Height, cmd166 (5.10)168 (7.27)167 (7.05)0.422
 Total tissue fat, % (DXA)e37.7 (7.26)33.4 (7.03)30.9 (6.97)<0.001
 Systolic blood pressure, mmHgd116 (12.5)112 (10.9)111 (9.8)0.055
Serum samplesd
 Total cholesterol, mmol/L4.24 (0.85)4.27 (0.73)4.60 (0.67)0.021
 Cholesterol/HDL-C ratio3.67 (0.89)2.93 (0.47)2.43 (0.43)<0.001
 Triglycerides, mmol/L0.94 (0.55)1.00 (1.68)0.65 (0.23)0.123
 CRP, nmol/L5.55 (5.01)4.85 (3.92)4.68 (2.00)0.413
 SHBG, nmol/L46.2 (18.3)50.5 (16.5)59.4 (21.9)<0.001
Serum hormonesf
 Estradiol, early follicular, nmol/L0.157 (0.080)0.138 (0.036)0.146 (0.061)0.215
 Estradiol, late follicular, nmol/L0.363 (0.273)0.481 (0.348)0.486 (0.307)0.040
 Estradiol, luteal, nmol/L0.404 (0.200)0.453 (0.199)0.434 (0.202)0.369
 Progesterone, early follicular, nmol/L5.97 (7.62)3.49 (2.93)5.17 (7.30)0.068
 Progesterone, late follicular, nmol/L4.54 (6.39)5.54 (8.515.82 (7.95)0.607
 Progesterone, luteal, nmol/L30.8 (19.7)38.5 (19.9)38.6 (20.2)0.037
Salivary hormones
 Mid-menstrual estradiol, pmol/Lg20.3 (10.1)17.3 (8.81)17.4 (7.64)0.107
 Luteal progesterone, pmol/Lh141 (81.0)137 (76.0)154 (61.7)0.443
Lifestyle factorsc
 Current smokers, %30.310.625.40.018
 Alcohol units per week, U1.96 (2.54)3.06 (3.29)3.71 (4.09)0.012
 Energy intake, kJ/d7893 (1,898)8,066 (1,928)8,460 (1,799)0.210
 Previous use of OC, %87.977.384.80.242
 Leisure time MET, h per wk64.2 (147)50.7 (35.2)58.4 (41.9)0.671
Mammographic densitye
 Absolute density, cm227.1 (19.2)40.9 (27.2)36.6 (21.4)0.002
 Percent density, %20.9 (16.7)31.9 (17.6)36.9 (19.2)<0.001

Abbreviations: E2, 17β-estradiol; One MET is defined as the energy cost of sitting quietly and is equivalent to a caloric consumption of 1 kcal/kg/hour; OC, oral contraceptives.

  • aNumbers may vary due to missing information.

  • bOne-way ANOVA or χ2 test, significance level P < 0.05.

  • cQuestionnaires.

  • dMeasurements at days 1–5 after onset of menstrual cycle.

  • eMeasurements at days 7–12 after onset of menstrual cycle.

  • fSerum hormone samples after onset of menstrual cycle: early follicular phase (days 1–5 after onset), late follicular phase (days 7–12 after onset), luteal phase (21–25 after onset).

  • gDaily salivary estradiol samples, aligned cycle days −7 to +6.

  • hDaily salivary progesterone samples, aligned cycle days 0 to +9.