ICD-10-CM 2027 diagnosis code
O99.42Diseases of the circulatory system complicating childbirth
O99.42 is a valid, billable ICD-10-CM code for diseases of the circulatory system complicating childbirth. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.
Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data
About O99.42
O99.42 is the ICD-10-CM diagnosis code for diseases of the circulatory system complicating childbirth. It belongs to category O99 (other maternal diseases classifiable elsewhere but complicating pregnancy, childbirth and the puerperium), block O94-O9A (other obstetric conditions, not elsewhere classified) and chapter 15 (pregnancy, childbirth and the puerperium). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.
Within O99.4 (diseases of the circulatory system complicating pregnancy, childbirth and the puerperium), O99.42 is specifically for diseases of the circulatory system complicating childbirth. Related codes cover pregnancy (O99.41) and the puerperium (O99.43).
Use an additional code to identify specific condition.
As a secondary diagnosis it is an MCC (major complication or comorbidity), which can move an inpatient stay into the highest-paying "with MCC" MS-DRG of its family, unless the principal diagnosis excludes it.
In MS-DRG v44.0, it is part of the grouping logic for DRG 998 (Principal Diagnosis Invalid as Discharge Diagnosis), in MDC 14 (Pregnancy, Childbirth and the Puerperium), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
The Medicare Code Editor treats this as a maternity diagnosis, expected only for patients age 9 through 64.
It is on the CMS list of diagnoses consistent only with female patients (the sex-conflict edit itself was retired in FY2025).
It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.
Before ICD-10, this condition was coded in ICD-9-CM as 674.01 (cerebrovascular disorders in the puerperium, delivered, with or without mention of antepartum condition) and 674.02 (cerebrovascular disorders in the puerperium, delivered, with mention of postpartum complication).
Notes that apply from higher levels
Instructions written at a parent level also apply to O99.42.
› From O99.4 Diseases of the circulatory system complicating pregnancy, childbirth and the puerperium
› From O99 Other maternal diseases classifiable elsewhere but complicating pregnancy, childbirth and the puerperium
- conditions which complicate the pregnant state, are aggravated by the pregnancy or are a main reason for obstetric care
- code to identify specific condition
Broader instructions also apply from Chapter 15: Pregnancy, childbirth and the puerperium.
Alphabetic index entries
1 entriesTerms in the official ICD-10-CM index that lead to O99.42.
MS-DRG v44.0 grouping
All DRGs →Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.
MDC 14 · Pregnancy, Childbirth and the Puerperium
ICD-9-CM equivalent
Converter →- 674.01Cerebrovascular disorders in the puerperium, delivered, with or without mention of antepartum conditionapproximate
- 674.02Cerebrovascular disorders in the puerperium, delivered, with mention of postpartum complicationapproximate
From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.
Code history
- 2016
- 2017
- 2018
- 2019
- 2020
- 2021
- 2022
- 2023
- 2024
- 2025
- 2026
- 2027
- FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
- No changes since FY2016.
Common questions about O99.42
Is O99.42 billable?
- Yes. O99.42 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can O99.42 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict O99.42 as a principal diagnosis.
Is O99.42 a CC or MCC?
- O99.42 is an MCC (major complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.
What DRG does O99.42 group to?
- O99.42 is used in the MS-DRG v44.0 logic for MS-DRG 998 (Principal Diagnosis Invalid as Discharge Diagnosis). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.
What is the ICD-9 code for O99.42?
- The CMS General Equivalence Mappings map O99.42 to ICD-9-CM 674.01 and 674.02.