2027 ICD-10-CM Diagnosis Code O99.42Diseases of the circulatory system complicating childbirth
ICD-10-CM Codes›O00-O9A›O94-O9A›O99
- Billable — Valid for Submission
- MCC — Major Complication or Comorbidity
- Not Chronic
O99.42 is a billable ICD-10-CM diagnosis code for diseases of the circulatory system complicating childbirth. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 998. As a secondary diagnosis, it counts as a major complication or comorbidity (MCC) and places an inpatient stay in the highest severity level of its MS-DRG family. It does not count, however, when the principal diagnosis is one of 227 closely related codes. The code is restricted by the Medicare Code Editor to maternity cases (age 9 through 64). Coders also document this condition as aortic valve disorder in mother complicating childbirth. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Complications specified during childbirth.
Code Identity
Code Classification
Code EditsBilling
Medicare Code Editor checks that affect claim validity for O99.42.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Aortic valve disorder in mother complicating childbirth
- Cardiac arrhythmia during pregnancy
- Cardiac arrhythmia in mother complicating childbirth
- Congenital cardiovascular anomaly in mother complicating childbirth
- Congenital cardiovascular disorders during pregnancy, childbirth and the puerperium
- Heart disease in mother complicating childbirth
- Heart disease in mother complicating pregnancy, childbirth AND/OR puerperium
- Heart murmur during pregnancy
- Heart murmur in mother in childbirth
- Mitral valve disorder in mother complicating childbirth
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to O99.42: its own notes plus those printed at O99.4, O99, and Chapter 15. A note printed at a category, block or chapter applies to every code under it.
Includes
Further defines, or gives examples of, the content of the category.
- conditions which complicate the pregnant state, are aggravated by the pregnancy or are a main reason for obstetric care
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
- peripartum cardiomyopathy (O90.3)
- supervision of normal pregnancy (Z34.-)
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
Use Additional Code
Add a second code, after this one, to fully describe the condition.
- code to identify specific condition
- code, if applicable, from category Z3A, Weeks of gestation, to identify the specific week of the pregnancy, if known.
Notes
General instructions on how these codes are used.
- 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
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name O99.42, its category, or a range that includes it.
Excludes1 1
These codes carry an Excludes1 note naming O99.42: they are not reported together with it, unless the two conditions are unrelated.
Code First 1
These codes say to code first a condition named in the note, and O99.42 is one of the conditions named.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Childbirth Problems
Childbirth is the process of giving birth to a baby. It includes labor and delivery. Usually everything goes well, but problems can happen. They may cause a risk to the mother, baby, or both. Some of the more common childbirth problems include:
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert O99.42 to ICD-9-CMHistory
Code HistoryHistory
Questions About O99.42Overview
What is the ICD-10 code for diseases of the circulatory system complicating childbirth?
The ICD-10-CM code for diseases of the circulatory system complicating childbirth is O99.42 (sometimes written as O9942). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is O99.42 a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report diseases of the circulatory system complicating childbirth on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does O99.42 group to?
When diseases of the circulatory system complicating childbirth is the principal diagnosis on an inpatient stay, it groups to MS-DRG 998 (principal Diagnosis Invalid as Discharge Diagnosis), which carries a relative weight of 0. Higher weights mean higher Medicare reimbursement.
Is O99.42 a CC or MCC?
CMS lists O99.42 as an MCC (major complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it places the inpatient stay in the highest-weighted DRG of its severity family. It does not count when the principal diagnosis is one of the 227 closely related codes in its exclusion list.
Who can O99.42 be reported for?
The Medicare Code Editor checks diseases of the circulatory system complicating childbirth against patient demographics: this code is intended for maternity cases (age 9 through 64). Claims outside these limits are flagged as inconsistent.
