Table 2.
Regression of key baseline characteristics and mean discrepancy between gestation estimated by ultrasonography and by reported LMP in ZAPPS analysis cohort (n=942).
| Characteristic | No. | Mean US–LMP discrepancy, d | Unadjusted analysisa | Adjusted analysisa | ||
|---|---|---|---|---|---|---|
| Regression coefficient (95% CI) | P valueb | Regression coefficient (95% CI) | P valueb | |||
| Age, y (continuous) | 942 | 2.21 | 0.05 (−0.12 to 0.22) | 0.546 | 0.13 (−0.07 to 0.33) | 0.196 |
| Education | ||||||
| None | 13 | 5.77 | 5.72 (−3.16 to 14.59) | 0.206 | 3.84 (−5.03 to 12.71) | 0.396 |
| Primary | 398 | 2.49 | 2.43 (−0.74 to 5.60) | 0.132 | 1.65 (−1.68 to 4.99) | 0.331 |
| Secondary | 412 | 2.44 | 2.38 (−0.78 to 5.54) | 0.139 | 1.77 (−1.45 to 4.98) | 0.281 |
| Post-secondary | 119 | 0.06 | 1 (reference) | 1 (reference) | ||
| BMI | ||||||
| <18.5 | 47 | 4.11 | 2.07 (−2.57 to 6.70) | 0.381 | 2.60 (−2.00 to 7.20) | 0.267 |
| 18.5–24 | 509 | 2.04 | 1 (reference) | 1 (reference) | ||
| ≥25 | 386 | 2.20 | 0.16 (−1.89 to 2.21) | 0.880 | 0.28 (−1.89 to 2.45) | 0.799 |
| Parity | ||||||
| 0 | 352 | 1.88 | −0.52 (−2.57 to 1.53) | 0.617 | ||
| ≥1 | 590 | 2.40 | 1 (reference) | |||
| Prior spontaneous abortion | ||||||
| 0 | 810 | 2.68 | 3.40 (0.56–6.25) | 0.019 | 1.34 (−2.23 to 4.92) | 0.461 |
| ≥1 | 132 | −0.72 | 1 (reference) | 1 (reference) | ||
| Vaginal bleeding at enrollment | ||||||
| No | 867 | 2.25 | 1 (reference) | 1 (reference) | ||
| Yes | 75 | 1.71 | −0.54 (−4.20 to 3.11) | 0.771 | 0.26 (−3.42 to 3.94) | 0.891 |
| HIV | ||||||
| No | 747 | 1.90 | 1 (reference) | 1 (reference) | ||
| Yes | 195 | 3.40 | 1.90 (−0.94 to 3.95) | 0.226 | 0.92 (−1.59 to 3.44) | 0.471 |
| Prior preterm birth | ||||||
| Nulliparous | 352 | 1.88 | 1.53 (−0.88 to 3.94) | 0.214 | 1.63 (−1.52 to 4.78) | 0.310 |
| 0 | 305 | 4.31 | 3.96 (1.47–6.45) | 0.002 | 2.92 (−0.03 to 5.88) | 0.053 |
| ≥1 | 285 | 0.35 | 1 (reference) | 1 (reference) | ||
| Ultrasonography-estimated gestational age, wk | ||||||
| <14 | 300 | −1.22 | 1 (reference) | 1 (reference) | ||
| ≥14 | 642 | 3.81 | 5.02 (2.92–7.12) | <0.001 | 4.58 (2.43–6.74) | <0.001 |
Abbreviations: BMI, body mass index (calculated as weight in kilograms divided by the square of height in meters); LMP, last menstrual period; US–LMP, ultrasonography and last menstrual period; ZAPPS, Zambian Prematurity Prevention Study.
a
Model adjusted for all covariates listed in Table 2, except parity.
b
P values calculated by regression for unadjusted and adjusted estimates and were considered significant at <0.05.