ICD-10-CM > O00-O9A > O30-O48 > O36 > O36.1 > O36.19 > O36.199 O36.199 Maternal care for other isoimmunization, unspecified trimester Non-Billable/Non-Specific Codes O36.1990..., not applicable or unspecifiedO36.1991..., fetus 1O36.1992..., fetus 2O36.1993..., fetus 3O36.1994..., fetus 4O36.1995..., fetus 5O36.1999..., other fetus