Table 1 Descriptive statistics for the discovery and replication samples
Variables | Discovery | Replication |
|---|---|---|
Age, year | ||
 Median | 33 | 66 |
 Range | 30–36 | 56–80 |
Gestational age, week | ||
 Median | 39 | 0 (weeks before term) |
 Range | 33–42 | 0–8 (weeks before term) |
 Report method | DMBR | Midwife |
Sample size | ||
 Male | 78 | 192 |
 Female | 66 | 158 |
Total | 144 | 350 |
PTB | 26 | 40 (more than 3Â weeks before term) |