O35 ICD-10-CM Code: Maternal care for known or suspected fetal abnormality and damage

O35 is the ICD-10-CM diagnosis code for maternal care for known or suspected fetal abnormality and damage. O35 sits in the ICD-10-CM chapter for pregnancy, childbirth and the puerperium (o00-o9a), within the section covering maternal care related to the fetus and amniotic cavity and possible delivery problems (o30-o48).

Header codes like O35 cannot be reported on claims directly, they organize child codes that share clinical context but the actual diagnosis must be coded to the highest level of specificity supported by the documentation. Coders should look at O35's child codes and select the one that matches the patient's documented presentation, since payers reject header codes submitted as the primary diagnosis. For risk adjustment workflows, header codes never contribute to a Medicare Advantage member's RAF score on their own; only billable child codes that happen to map to a payment HCC affect risk-adjusted plan payments.