Table 1.
Distributions of selected characteristics and sex hormone concentrations among postmenopausal women overall as well as stratified by tertiles of plasma prolactin, the Singapore Chinese Health Study
| Overall | Plasma prolactin
|
|||
|---|---|---|---|---|
| First tertile | Second tertile | Third tertile | ||
| n | 442 | 148 | 150 | 144 |
| Mean (SD) age at blood draw, year | 64.5 (4.8) | 63.9 (4.8) | 64.5 (5.0) | 65.0 (4.8) |
| Mean hours from last meal to blood draw | 5.4 (5.2) | 5.4 (5.1) | 4.7 (4.7) | 6.0 (5.8) |
| Education level, n (%) | ||||
| No formal | 158 (35.8) | 57 (38.5) | 56 (37.3) | 45 (31.3) |
| Primary | 192 (43.4) | 61 (41.2) | 64 (42.7) | 67 (46.5) |
| ≥ Secondary | 92 (20.8) | 30 (20.3) | 30 (20.0) | 32 (22.2) |
| Mean (SD) BMI, kg/m2 | 23.6 (3.3) | 23.7 (3.3) | 23.7 (3.4) | 23.3 (3.3) |
| Ever smoker, n (%) | 26 (5.9) | 7 (4.7) | 11 (7.3) | 8 (5.6) |
| Ever alcohol use, n (%) | 21 (4.8) | 8 (5.4) | 7 (4.7) | 6 (4.2) |
| Natural menopausal type, n (%) | 403 (91.2) | 136 (91.9) | 135 (90.0) | 132 (91.7) |
| Age at menopause, n (%), year | ||||
| < 45 | 40 (9.1) | 12 (8.1) | 16 (10.7) | 12 (8.3) |
| 46–49 | 108 (24.4) | 36 (24.3) | 34 (22.7) | 38 (26.4) |
| ≥ 50 | 294 (66.5) | 100 (67.7) | 100 (66.7) | 94 (65.3) |
| Age at menarche, n (%), year | ||||
| < 13 | 51 (11.5) | 16 (10.8) | 12 (8.0) | 23 (16.0) |
| 13–14 | 184 (41.6) | 64 (43.2) | 61 (40.7) | 59 (41.0) |
| 15–16 | 160 (36.2) | 58 (39.2) | 57 (38.0) | 45 (31.3) |
| ≥ 17 | 47 (10.6) | 10 (6.8) | 20 (13.3) | 17 (11.8) |
| Number of births | ||||
| 0 | 25 (5.7) | 9 (6.1) | 8 (5.3) | 8 (5.6) |
| 1–2 | 119 (26.9) | 39 (26.4) | 42 (28.0) | 38 (26.4) |
| 3–4 | 182 (41.2) | 60 (40.5) | 67 (44.7) | 55 (38.2) |
| ≥ 5 | 116 (26.2) | 40 (27.0) | 33 (22.0) | 43 (29.9) |
| Age at first birth, n (% parous), year | ||||
| ≤ 20 | 85 (19.2) | 24 (16.2) | 39 (26.0) | 22 (15.3) |
| 21–25 | 155 (35.1) | 61 (41.2) | 44 (29.3) | 50 (34.7) |
| 26–30 | 128 (29.0) | 42 (28.4) | 42 (28.0) | 44 (30.6) |
| ≥ 31 | 74 (16.7) | 21 (14.2) | 25 (16.7) | 28 (19.4) |
| Plasma hormones, geometric mean (95% CI)a | ||||
| Prolactin, ng/mL (n = 442) | 7.00 (6.66, 7.38) | 4.18 (3.96–4.42) | 6.64 (6.3–7.00) | 12.60 (11.94–13.3)† |
| Estrone, pg/mL (n = 440) | 25.7 (24.8, 26.7) | 27.1 (25.4–28.9) | 26.0 (24.4–27.8) | 24.1 (22.6–25.8)† |
| Estradiol, pg/mL (n = 391) | 8.04 (7.70, 8.38) | 8.34 (7.78–8.94) | 8.20 (7.64–8.82) | 7.54 (7.00–8.12) |
| Free estradiol, pg/mL (n = 395) | 0.24 (0.22, 0.24) | 0.24 (0.22–0.26) | 0.24 (0.22–0.26) | 0.22 (0.20–0.24) |
| Testosterone, pg/mL (n = 442) | 19.3 (18.4, 20.2) | 19.1 (17.5–20.8) | 19.7 (18.0–21.4) | 19.1 (17.5–20.8) |
| SHBG, nmol/L (n = 442) | 40.0 (38.3, 41.6) | 40.2 (37.4–43.2) | 37.6 (35.0–40.4) | 42.2 (39.2–45.4) |
| Androstenedione, pg/mL (n = 442) | 426.9 (407.6, 447.2) | 424.0 (391.3–459.5) | 432.6 (399.4–468.5) | 424.2 (391.0–460.2) |
a
Geometric means are adjusted for age at blood draw, time from last meal to specimen collection, and time of specimen collection
†
p value < 0.05