| Gestation weeks | ACS given (312) | No ACS (526) | Total |
| N (%) | N (%) | ||
| 27 | 18 (50.0) | 18 (50.0) | 36 |
| 28 | 20 (14.7) | 116 (85.3) | 136 |
| 29 | 15 (30.0) | 35 (70.0) | 50 |
| 30 | 23 (33.8) | 45 (66.2) | 68 |
| 31 | 27 (49.1) | 28 (50.9) | 55 |
| 32 | 44 (31.6) | 95 (68.4) | 139 |
| 33 | 64 (60.9) | 41 (39.1) | 105 |
| 34 | 101 (40.6) | 148 (59.4) | 249 |