2027 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 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

P08.21 is a billable ICD-10-CM diagnosis code for post-term newborn. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 795. 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

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to P08.21: its own notes plus those printed at P08 and Chapter 16. 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.

From P08 Disorders of newborn related to long gestation and high birth weight applies to 4 codes
  • the listed conditions, without further specification, as causes of morbidity or additional care, in newborn
From Chapter 16 (P00-P96) Certain conditions originating in the perinatal period applies to 463 codes
  • conditions that have their origin in the fetal or perinatal period (before birth through the first 28 days after birth) even if morbidity occurs later

Applicable To

Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.

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

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.

From Chapter 16 (P00-P96) Certain conditions originating in the perinatal period applies to 463 codes
  • congenital malformations, deformations and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • tetanus neonatorum (A33)

Notes

General instructions on how these codes are used.

From P08 Disorders of newborn related to long gestation and high birth weight applies to 4 codes
  • When both birth weight and gestational age of the newborn are available, priority of assignment should be given to birth weight
From Chapter 16 (P00-P96) Certain conditions originating in the perinatal period applies to 463 codes
  • Codes from this chapter are for use on newborn records only, never on maternal records

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

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.

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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About P08.21Overview

What is the ICD-10 code for post-term newborn?

The ICD-10-CM code for post-term newborn is P08.21 (sometimes written as P0821). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

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, 2026 through September 30, 2027.

What MS-DRG does P08.21 group to?

When post-term newborn is the principal diagnosis on an inpatient stay, it groups to MS-DRG 795 (normal Newborn), which carries a relative weight of 0.2022. Higher weights mean higher Medicare reimbursement.

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.