2026 ICD-10-CM Diagnosis Code P08.21Post-term newborn

ICD-10-CM Codes›P00–P96›P05-P08›P08

ICD-10-CM P08.21
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

P08.21 is a billable ICD-10-CM diagnosis code for post-term newborn. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified and unspecified perinatal conditions.

Code Identity

ICD-10-CM Code
P08.21
Billable Status
Yes — Valid for Submission
Code Describes
Post-term newborn
Short Description
Post-term newborn
Same as the full description in the CMS dataset.
Parent Code
P08.2
Late newborn, not heavy for gestational age

Code Classification

ChapterP00–P96Certain conditions originating in the perinatal period
SectionP05-P08Disorders of newborn related to length of gestation and fetal growth
CategoryP08Disorders of newborn related to long gestation and high birth weight
This CodeP08.21Post-term newborn

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Newborn with gestation period over 40 completed weeks to 42 completed weeks

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Newborn(infant) (liveborn) (singleton)
      • post-term
    • Post-term(40-42 weeks) (pregnancy) (mother)
      • infant

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR PNL013
Other specified and unspecified perinatal conditions
Default principal diagnosis: inpatient Yes · outpatient Yes

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 P08.21 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
766.21 Post-term infant
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About P08.21Overview

Is P08.21 (Late newborn, not heavy for gestational age) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report post-term newborn on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What is the ICD-9 equivalent of P08.21?

Under the General Equivalence Mappings, post-term newborn converts to ICD-9-CM 766.21 (post-term infant). The mapping is a direct match.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.