Table 2.
Reproductive hormones, menstrual cycle characteristics and the proportion of anovulatory cycles by tertile of average past-week physical activity within each cycle (N=509 cycles)
| Average past-week physical activity within each cycle* | |||||||||
|---|---|---|---|---|---|---|---|---|---|
|
| |||||||||
| Cycle characteristics | Total Number of Cycles (N=509†) | Lowest Tertile (median =9 MET-h/week) (n=168) | Middle Tertile (median =24 MET-h/week) (n=168) | Highest Tertile (median =66 MET-h/week) (n=173) | P-value‡ | ||||
| Reproductive hormones§, mean (95% CI) | |||||||||
| Estradiol (pg/mL) | 82.6 (79.2, 86.2) | 81.8 (77.0, 87.0) | 82.6 (77.9, 87.5) | 83.4 (78.4, 88.6) | 0.90 | ||||
| Progesterone (ng/mL) | 1.4 (1.3, 1.5) | 1.4 (1.3, 1.6) | 1.4 (1.3, 1.5) | 1.3 (1.2, 1.4) | 0.22 | ||||
| LH (ng/mL) | 6.3 (6.0, 6.5) | 6.0 (5.6, 6.3) | 6.3 (6.0, 6.7) | 6.5 (6.2, 7.0) | 0.09 | ||||
| FSH (mIU/mL) | 5.4 (5.2, 5.6) | 5.3 (5.1, 5.6) | 5.4 (5.1, 5.7) | 5.4 (5.1, 5.7) | 0.91 | ||||
| Testosterone (ng/dL) | 27.8 (26.6, 29.0) | 28.1 (26.8, 29.4) | 27.6 (26.4, 28.9) | 27.7 (26.4, 29.0) | 0.61 | ||||
| Leptin (ng/mL) | 19.5 (17.9, 21.2) | 20.4 (18.6, 22.4) | 19.9 (18.2, 21.8) | 18.2 (16.6, 20.0) | <0.01 | ||||
| Menstrual cycle characteristics, mean (95% CI) | |||||||||
| Menstrual cycle length, days|| | 28.8 (28.4, 29.3) | 28.6 (27.9, 29.3) | 28.6 (28.0, 29.3) | 29.3 (28.6, 30.0) | 0.27 | ||||
| Follicular phase length, days¶ | 15.3 (14.9, 15.8) | 14.8 (14.1, 15.4) | 15.1 (14.4, 15.7) | 16.1 (15.4, 16.8) | <0.01 | ||||
| Luteal phase length, days¶ | 13.9 (13.7, 14.1) | 14.1 (13.7, 14.5) | 13.9 (13.5, 14.3) | 13.7 (13.3, 14.1) | 0.42 | ||||
| Menses length, days# | 5.4 (5.2, 5.5) | 5.2 (5.0, 5.5) | 5.4 (5.2, 5.6) | 5.5 (5.2, 5.7) | 0.26 | ||||
| Total blood loss, g## | 43.8 (38.9, 49.3) | 42.7 (36.3, 50.3) | 42.2 (36.1, 49.2) | 46.5 (39.4, 54.8) | 0.56 | ||||
| Anovulatory cycles**, n (column %) | 42 (8.3%) | 12 (7.1%) | 13 (7.7%) | 17 (9.8%) | 0.70 | ||||
SD= standard deviation; CI= confidence interval; FSH= follicle-stimulating hormone; LH= luteinizing hormone
Average past-week physical activity within each cycle tertile cut-points were 15.4 and 36.6 MET-h/week.
250 women were followed for 2 cycles, 9 women were followed for 1 cycle.
P-value for continuous measures assessed by Type III effects from unadjusted linear mixed models. Anovulatory cycle p-value assessed by Type III effects from unadjusted generalized linear regression.
Geometric mean calculated within-women using up to 8 measurements over the cycle. Testing performed on log hormone mean and then transformed by exponentiation for table display.
Menstrual cycle length available for 476 cycles.
Follicular phase length available for 467 ovulatory cycles; luteal phase length available for 443 ovulatory cycles.
Menses length available for 497 cycles.
Total blood loss available for 467 cycles. Geometric mean calculated within-women using up to 2 measurements over the study. Testing performed on log total blood loss mean and then transformed by exponentiation for table display.
Anovulatory cycles defined as having peak progesterone concentration < 5 ng/mL and no luteinizing hormone peak detected in serum during the latter half of the cycle.