Coding and coverage · ICD-10-CM

O99

O99.3 Mental disorders and diseases of the nervous system complicating pregnancy, childbirth and the puerperium

Not billable (header)Chapter 15

Report one of the more specific codes below.

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Codes under this one

  • O99.31 Alcohol use complicating pregnancy, childbirth, and the puerperiumHeader
  • O99.32 Drug use complicating pregnancy, childbirth, and the puerperiumHeader
  • O99.33 Tobacco use disorder complicating pregnancy, childbirth, and the puerperiumHeader
  • O99.34 Other mental disorders complicating pregnancy, childbirth, and the puerperiumHeader
  • O99.35 Diseases of the nervous system complicating pregnancy, childbirth, and the puerperiumHeader

Instructional notes

Chapter 15

Excludes1Not coded here: never report with this code, except when the two conditions are unrelated.
  • supervision of normal pregnancy (Z34.-)
Excludes2Not included here: the patient may have both; report both when both are present.
  • mental and behavioral disorders associated with the puerperium (F53.-)
  • obstetrical tetanus (A34)
  • postpartum necrosis of pituitary gland (E23.0)
  • puerperal osteomalacia (M83.0)
Use additional codeAdd a second code for the full picture.
  • code, if applicable, from category Z3A, Weeks of gestation, to identify the specific week of the pregnancy, if known.
Notes
  • CODES FROM THIS CHAPTER ARE FOR USE ONLY ON MATERNAL RECORDS, NEVER ON NEWBORN RECORDS
  • Codes from this chapter are for use for conditions related to or aggravated by the pregnancy, childbirth, or by the puerperium (maternal causes or obstetric causes)
  • Trimesters are counted from the first day of the last menstrual period. They are defined as follows:
  • 1st trimester- less than 14 weeks 0 days
  • 2nd trimester- 14 weeks 0 days to less than 28 weeks 0 days
  • 3rd trimester- 28 weeks 0 days until delivery

O99

Excludes2Not included here: the patient may have both; report both when both are present.
  • when the reason for maternal care is that the condition is known or suspected to have affected the fetus (O35-O36)
Use additional codeAdd a second code for the full picture.
  • code to identify specific condition
Includes
  • conditions which complicate the pregnant state, are aggravated by the pregnancy or are a main reason for obstetric care

Chapter 15: Pregnancy, childbirth and the puerperium (O00-O9A) · O94-O9A Other obstetric conditions, not elsewhere classified (O94-O9A)

Source: ICD-10-CM FY 2027 code descriptions and tabular list (CMS and CDC National Center for Health Statistics), effective 2026-10-01 through 2027-09-30 · CMS ICD-10 files. HCC mapping: CMS-HCC V28, payment year 2027. As of 2026-11-04.

Coverage and payment depend on the claim details; confirm with the Medicare Administrative Contractor.