Table 4.
Association of Categorical CRP with Luteal Phase Lengtha, Long Luteal Phase, and Short Luteal Phase
| CRP (mg/L) | No. Cycles | Adjusted b Δ Luteal Phase Length, days (95% CI) | Adjusted c Δ in Luteal Phase Length, days (95% CI) | Adjusted d Δ in Luteal Phase Length, days (95% CI) | |
| CRP, per ln-unit increase | 690 | 0.15 (−0.11, 0.40) | 0.24 (−0.09, 0.57) | 0.37(−0.13, 0.88) | |
| <1 | 353 | Reference | |||
| ≥1– <3 | 201 | 0.21 (−0.65, 1.07) | 0.16 (−0.87, 1.20) | 1.22 (−0.32, 2.76) | |
| ≥ 3– <10 | 80 | 0.13 (−1.06, 1.33) | −0.19 (−1.68, 1.29) | 0.44 (−1.87, 2.75) | |
| ≥ 10 | 56 | 0.17 (−1.19, 1.53) | 0.76 (−0.97, 2.49) | 1.14 (−1.50, 3.78) | |
| Joint Significance | 0.97 | 0.80 | 0.46 | ||
| Long Luteal Phase | |||||
| aOR (95% CI) b | aOR (95% CI) c | aOR (95% CI) d | aOR (95% CI) e | ||
| CRP, per ln-unit increase | 551 | 1.17 (0.96, 1.43) | 1.26 (0.99, 1.61) | 1.26 (0.91, 1.74) | 1.32 (1.02, 1.69) |
| <1 | 282 | Reference | |||
| ≥1– <3 | 168 | 1.17 (0.61, 2.27) | 1.12 (0.49, 2.53) | 2.03 (0.77, 5.37) | 1.25 (0.52, 3.02) |
| ≥ 3– <10 | 58 | 1.35 (0.54, 3.37) | 1.21(0.32, 4.53) | 3.20 (0.52, 19.6) | 1.87 (0.53, 6.56) |
| ≥ 10 | 43 | 1.62 (0.55, 4.78) | 2.03 (0.59, 7.06) | 0.84 (0.07,10.03) | 2.72 (0.77, 9.58) |
| Joint Significance | 0.79 | 0.74 | 0.38 | 0.38 | |
| Short Luteal Phase | |||||
| aOR (95% CI) b | aOR (95% CI) c | aOR (95% CI) d | aOR (95% CI) e | ||
| CRP, per ln-unit increase | 635 | 1.08 (0.94, 1.25) | 1.06 (0.88, 1.27) | 1.11 (0.83, 1.50) | 0.99 (0.79, 1.23) |
| <1 | 326 | Reference | |||
| ≥1– <3 | 185 | 1.03 (0.62, 1.70) | 0.79 (0.42, 1.50) | 0.86 (0.37, 2.28) | 0.74 (0.37, 1.47) |
| ≥ 3– <10 | 74 | 1.28 (0.65, 2.52) | 1.48 (0.67, 3.29) | 2.22 (0.60, 8.23) | 1.10 (0.48, 2.55) |
| ≥ 10 | 50 | 1.63 (0.83, 3.19) | 1.47 (0.61, 3.56) | 0.95 (0.22, 4.15) | 1.15 (0.42, 3.16) |
| Joint Significance | 0.51 | 0.38 | 0.59 | 0.71 | |
a
To achieve normality of the model residuals, the continuous analysis was limited to phases between 5 and 45 days long. Results are displayed as change in phase in days for a given CRP category, compared to the reference group.
b
Adjusted for age
c
Adjusted for age, race, education, BMI, time since oral contraceptive use, alcohol, smoking, caffeine consumption, and exercise
d
Sensitivity analysis of luteal phase length with ovulation determined by OPK (Cycle N=326)
e
Sensitivity analysis the association of categorical CRP with long luteal phase weighted by the inverse of cycles contributed by each woman