TABLE 3.
Univariate maternal determinants of CTX in EP and LP (Fisher-Yates scores), SD increase per unit change in maternal predictor in those with both an EP and an LP measure1
| EP CTX (14 weeks of gestation) | LP CTX2 (34 weeks of gestation) | Δ CTX2,3 | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Exposure | n | β4 (95% CI) | P value | n | β4 (95% CI) | P value | n | β (95% CI) | P value |
| Maternal age, y | 493 | −0.03 (−0.05, −0.01) | <0.001 | 469 | −0.03 (−0.04, −0.01) | 0.01 | 372 | −0.02 (−0.037, 0.002) | 0.07 |
| Strenuous exercise >1 h/wk (Y/N) | 440 | −0.10 (−0.36, 0.16) | 0.47 | 425 | −0.11 (−0.40, 0.18) | 0.47 | 329 | −0.17 (−0.50, 0.16) | 0.31 |
| Smoking in early pregnancy (Y/N) | 491 | 0.36 (0.05, 0.68) | 0.03 | 467 | −0.20 (−0.53, 0.13) | 0.24 | 370 | −0.20 (−0.57, 0.17) | 0.30 |
| Parity ≥1 (Y/N) | 491 | −0.48 (−0.66, −0.31) | <0.001 | 467 | −0.33 (−0.52, −0.15) | <0.001 | 371 | −0.11 (−0.32, 0.09) | 0.28 |
| Caucasian ethnicity (Y/N) | 490 | 0.17 (−0.25, 0.58) | 0.44 | 466 | 0.23 (−0.21, 0.67) | 0.31 | 369 | 0.33 (−0.20, 0.86) | 0.22 |
| Weight, kg | 493 | −0.01 (−0.01, 0.00) | 0.07 | 469 | 0.002 (−0.004, 0.008) | 0.50 | 372 | 0.01 (−0.001, 0.013) | 0.12 |
| Height, cm | 488 | −0.01 (−0.03, 0.00) | 0.05 | 465 | −0.02 (−0.03, −0.01) | 0.004 | 368 | −0.01 (−0.029, 0.004) | 0.13 |
| BMI, kg/cm2 | 488 | −0.01 (−0.03, 0.01) | 0.21 | 465 | 0.02 (−0.001, 0.034) | 0.07 | 368 | 0.02 (0.001, 0.041) | 0.04 |
| 14-wk 25(OH)D, nmol/L | 488 | 0.004 (−0.001, 0.009) | 0.14 | 496 | −0.004 (−0.010, 0.001) | 0.13 | 371 | −0.01 (−0.014, −0.001) | 0.03 |
| 14-wk calcium, mmol/L | 488 | 0.53 (−0.56, 1.62) | 0.34 | 496 | 0.67 (−0.36, 1.70) | 0.20 | 371 | 1.14 (−0.09, 2.38) | 0.07 |
| 34-wk 25(OH)D, nmol/L | 489 | −0.001 (−0.016, 0.003) | 0.55 | 364 | −0.003 (−0.009, 0.002) | 0.19 | |||
| 34-wk calcium, mmol/L | 488 | 0.15 (−0.63, 0.92) | 0.71 | 363 | 0.19 (−0.74, 1.11) | 0.70 | |||
| Change in 25(OH)D from 14 to 34 wk, nmol/L | 487 | 0.001 (−0.003, 0.005) | 0.60 | 363 | 0.001 (−0.004, 0.006) | 0.77 | |||
| Vitamin D–supplemented group (Y/N) | 498 | −0.18 (−0.35, −0.00) | 0.05 | 372 | −0.32 (−0.52, −0.11) | 0.002 | |||
| Season of delivery, summer (proxy for season of measurement) | 438 | 0.02 (−0.16, 0.21) | 0.81 | 488 | 0.07 (−0.11, 0.25) | 0.44 | 366 | 0.07 (−0.14, 0.27) | 0.52 |
1
CTX, C-terminal telopeptide of type I collagen; EP, early pregnancy; LP, late pregnancy; 25(OH)D, 25-hydroxyvitamin D.
2
SD change in urinary CTX (Fisher-Yates score) per unit exposure.
3
Adjusted for treatment group, except when associations between the vitamin D–supplemented group and CTX were being tested.
4
Conditional change in CTX (LP CTX adjusted for EP CTX), as z score.