Gestational age (the earliest in case of repeated US exams)—categories

P

First trimester (8 - 14 weeks)

Second trimester

Third trimester

N (%)

N (%)

N (%)

Any positive visible fetal abnormality detected by US

<0.001

Negative (no abnormality noticed)

473 (97.1)

992 (90.5)

454 (88.3)

Positive (abnormal)

14 (2.9)

104 (9.5)

60 (11.7)

Total

487 (100)

1096 (100)

514 (100)