Table 1.
Baseline Characteristics of Participants
| Characteristic | Deferred Scan (n=167) | Immediate Scan (n=168) |
|---|---|---|
| Age (y) | 31.0 (27.0–34.0) | 31.0 (26.0–35.0) |
| Body mass index (kg/m2) | 23.4 (21.2–27.8) | 24.4 (21.5–27.3) |
| Race | ||
| White | 65 (38.9) | 63 (37.5) |
| African American | 50 (29.9) | 58 (34.5) |
| Hispanic | 30 (18.0) | 20 (11.9) |
| Asian or Pacific Islander | 17 (10.2) | 22 (13.1) |
| Other | 5 (3.0) | 5 (3.0) |
| Gravidity | 2.0 (1.0–4.0) | 2.0 (1.0–4.0) |
| Parity | 1.0 (0.0–1.0) | 1.0 (0.0–1.0) |
| Gestational age (wk) | 21.0 (18.3–25.9) | 19.4 (18.1–25.6) |
| Comorbidity | 42 (25.2) | 37 (22.0) |
| History of preterm birth | 37 (22.2) | 41 (24.4) |
| History of cervical insufficiency | 12 (7.2) | 15 (8.9) |
| Known leiomyomas | 9 (5.4) | 8 (4.8) |
| Indication for examination | ||
| Routine screen | 80 (29.9) | 64 (38.1) |
| Transabdominal cervical shortening | 2 (1.2) | 1 (0.6) |
| History of cervical insufficiency | 7 (4.2) | 9 (5.4) |
| History of preterm birth | 28 (16.8) | 29 (17.3) |
| Multiple gestation | 14 (8.4) | 13 (7.7) |
| Prior cervical shortening | 33 (19.8) | 23 (13.7) |
| Concern for placenta previa | 16 (9.6) | 18 (10.7) |
| Follow-up cervical cerclage | 17 (10.2) | 17 (10.1) |
| Other | 32 (19.2) | 25 (14.9) |
| Initial encounter | 105 (62.9) | 116 (69.0) |
| Reenrollments | 62 (37.1) | 52 (31.0) |
Data are median (interquartile range) or n (%).