Table 1.
Cohort characteristics overall and stratified by anemia status at enrollment
| N (%) |
||||
|---|---|---|---|---|
| Anemia status |
||||
| Characteristic | Overall (N=1447) | Positive (N=138) | Negative (N=884) | Unknown (N=425) |
|
| ||||
| Spontaneous preterm birth | 120 (9.9) | 15 (12.4) | 70 (9.6) | 35 (9.7) |
| Missing | 239 | 17 | 157 | 65 |
| At enrollment | ||||
| Gestational age (weeks) | ||||
| Median (IQR) | 16.1 (13.3, 18.3) | 16.9 (14.7, 18.9) | 15.9 (12.9, 18.1) | 16.6 (13.6, 18.6) |
| First trimester | 432 (29.9) | 29 (21) | 286 (32.4) | 117 (27.5) |
| Missing | 0 | 0 | 0 | 0 |
| Maternal age | ||||
| Median (IQR) | 27 (23, 32) | 27 (22, 33) | 27 (23, 32) | 27 (22, 31) |
| <20 years | 111 (7.9) | 11 (8.3) | 59 (6.9) | 41 (9.8) |
| 20–34 years | 1113 (79.2) | 102 (76.7) | 677 (79.2) | 334 (79.9) |
| ≥35 years | 182 (12.9) | 20 (15) | 119 (13.9) | 43 (10.3) |
| Missing | 41 | 5 | 29 | 7 |
| HIV+ | 349 (24.2) | 58 (42) | 195 (22.1) | 96 (22.7) |
| Missing | 3 | 0 | 0 | 3 |
| Nulliparous | 457 (31.6) | 40 (29) | 286 (32.4) | 131 (30.8) |
| Missing | 0 | 0 | 0 | 0 |
| Prior preterm birth | 410 (28.3) | 40 (29) | 258 (29.2) | 112 (26.4) |
| Missing | 0 | 0 | 0 | 0 |
| Prior stillbirth | 126 (9.3) | 15 (11.6) | 80 (9.6) | 31 (7.8) |
| Missing | 85 | 9 | 48 | 28 |
Abbreviations: IQR, interquartile range