| Positive structural fetal anomalies | Gestational age (the earliest in case of repeated US exams)—categories | P | ||
| First trimester (8 - 14 weeks) | Second trimester | Third trimester | ||
| N (%) | N (%) | N (%) | ||
| (Total n = 487) | (Total n = 1096) | (Total n = 514) | ||
| Abdominal wall anomalies | 1 (0.2) | 6 (0.5) | 1 (0.2) | 0.44 [NS] |
| Abnormalities of brain | 4 (0.8) | 31 (2.8) | 18 (3.5) | 0.017 |
| Extremities abnormalities | 3 (0.6) | 41 (3.7) | 17 (3.3) | 0.002 |
| Face anomalies | 0 (0) | 4 (0.4) | 4 (0.8) | 0.14 [NS] |
| GIT anomalies | 4 (0.8) | 19 (1.7) | 22 (4.3) | <0.001 |
| Head anomalies | 3 (0.6) | 14 (1.3) | 5 (1) | 0.48 [NS] |
| Heart anomalies | 3 (0.6) | 18 (1.6) | 12 (2.3) | 0.09 [NS] |
| Abnormalities of neck and skin | 4 (0.8) | 10 (0.9) | 3 (0.6) | 0.79 [NS] |
| Spine anomalies | 3 (0.6) | 10 (0.9) | 6 (1.2) | 0.65 [NS] |
| Thorax anomalies | 6 (1.2) | 33 (3) | 15 (2.9) | 0.1 [NS] |
| Urinary tract abnormalities | 2 (0.4) | 35 (3.2) | 19 (3.7) | 0.002 |
| Abnormal genitalia | 1 (0.2) | 0 (0) | 2 (0.4) | 0.14 [NS] |
| Any positive visible fetal abnormality detected by US | 14 (2.9) | 104 (9.5) | 60 (11.7) | <0.001 |