ICD-10-CM > O00-O9A > O30-O48 > O35 > O35.1 > O35.12 O35.12 Maternal care for (suspected) chromosomal abnormality in fetus, Trisomy 18 Non-Billable/Non-Specific Codes O35.12X0..., not applicable or unspecifiedO35.12X1..., fetus 1O35.12X2..., fetus 2O35.12X3..., fetus 3O35.12X4..., fetus 4O35.12X5..., fetus 5O35.12X9..., other fetus