Table 3.
The effect of habitual, past-week, vigorous past-week and daily vigorous physical activity on the risk of sporadic anovulation (N=509 cycles).
| Physical activity exposure definition | All Cycles | Anovulatory Cycles | Unadjusted | Adjusted* | ||
|---|---|---|---|---|---|---|
| RR | 95% CI | RR | 95% CI | |||
| Habitual PA tertile†, N=509 | ||||||
| Highest | 171 | 10 (6%) | 0.64 | (0.28, 1.46) | 0.54 | (0.22, 1.28) |
| Middle | 169 | 17 (10%) | 1.13 | (0.52, 2.46) | 1.10 | (0.51, 2.37) |
| Lowest | 169 | 15 (9%) | Reference | Reference | ||
| Past-week PA tertile‡, N=509 | ||||||
| Highest | 174 | 15 (9%) | 1.23 | (0.60, 2.54) | 1.47 | (0.64, 3.36) |
| Middle | 168 | 15 (9%) | 1.17 | (0.58, 2.36) | 1.30 | (0.62, 2.70) |
| Lowest | 167 | 12 (7%) | Reference | Reference | ||
| Vigorous past-week PA tertile§, N=509 | ||||||
| Highest | 171 | 15 (9%) | 1.03 | (0.53, 1.98) | 1.08 | (0.53, 2.19) |
| Middle | 154 | 12 (8%) | 0.89 | (0.41, 1.94) | 0.97 | (0.44, 2.13) |
| Lowest | 184 | 15 (8%) | Reference | Reference | ||
| Daily vigorous PA||, N=505 | ||||||
| High (>15 minutes) | 171 | 17 (10%) | 1.34 | (0.75, 2.37) | 1.64 | (0.86, 3.12) |
| Low (0 to 15 minutes) | 334 | 21 (6%) | Reference | Reference | ||
PA= physical activity; RR= risk ratio; CI= confidence interval
Adjusted: age, body mass index, race, perceived stress; past-week and daily vigorous physical activity also adjusted for habitual physical activity. Two cycles were excluded from the adjusted analysis due to missing data on perceived stress.
Habitual physical activity tertile cut-points were 35.1 and 83.3 MET-h/week.
Past-week physical activity was averaged only over the first half of the cycle to ensure that the proper temporal ordering of the exposure-outcome relationship would be preserved. The tertile cut-points were 14.6 and 34.9 MET-h/week.
Vigorous past-week physical activity was averaged only over the first half of the cycle to ensure that the proper temporal ordering of the exposure-outcome relationship would be preserved. The tertile cut-points were 0.13 and 0.63 MET-h/week.
Daily vigorous activity was averaged only over the first half of the cycle to ensure that the proper temporal ordering of the exposure-outcome relationship would be preserved. Four cycles were missing data on daily vigorous physical activity during the first half of the cycle and were omitted from the analysis.