2026 ICD-10-CM Diagnosis Code P81.9Disturbance of temperature regulation of newborn, unspecified

ICD-10-CM Codes›P00–P96›P80-P83›P81

ICD-10-CM P81.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

P81.9 is a billable ICD-10-CM diagnosis code for disturbance of temperature regulation of newborn, unspecified. 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
P81.9
Billable Status
Yes — Valid for Submission
Code Describes
Disturbance of temperature regulation of newborn, unspecified
Short Description
Disturbance of temperature regulation of newborn, unsp
Parent Code
P81
Other disturbances of temperature regulation of newborn

Code Classification

ChapterP00–P96Certain conditions originating in the perinatal period
SectionP80-P83Conditions involving the integument and temperature regulation of newborn
CategoryP81Other disturbances of temperature regulation of newborn
This CodeP81.9Disturbance of temperature regulation of newborn, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute rise of fever
  • Biphasic fever
  • Body temperature above reference range
  • Central fever
  • Chill
  • Continuous fever
  • Disorder characterized by fever
  • Disturbance of temperature regulation of newborn
  • Falling phase of fever
  • Febrile leukopenia
  • Feeling feverish
  • Fever
  • Fever defervescence
  • Fever due to infection
  • Fever greater than 100.4 Fahrenheit
  • Fever of newborn
  • Fever with chills
  • Fever, diurnal variation
  • Feverish cold
  • Gradual fall of fever
  • Gradual rise of fever
  • Hyperthermia
  • Hyperthermia in newborn
  • Increased skin temperature
  • Intermittent fever
  • Irregular fever
  • Low grade pyrexia
  • Myoclonus associated with fever
  • Neurogenic hyperthermia
  • Perinatal disorder of skin and temperature regulation
  • Phase of fever - finding
  • Plateau phase of fever
  • Prolonged fever
  • Pyrexia of unknown origin
  • Pyrexia of unknown origin co-occurrent with human immunodeficiency virus infection
  • Rapid fall of fever
  • Remittent fever
  • Reversed diurnal fever
  • Rising phase of fever
  • Severe fever with thrombocytopenia syndrome
  • Shivering or rigors
  • Slightly remittent fever
  • Staircase fever
  • Sweating fever
  • Viral fever

Tabular List NotesGuidance

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

Inclusion Terms

  • Fever of newborn NOS

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.

    • Disorder(of)
      • temperature regulation, newborn
    • Disturbance(s)
      • temperature
        • regulation, newborn
    • Fever(inanition) (of unknown origin) (persistent) (with chills) (with rigor)
      • newborn
    • Hyperthermia(of unknown origin)
      • newborn
    • Newborn(infant) (liveborn) (singleton)
      • fever
    • Pyrexia(of unknown origin)
      • newborn

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

Clinical InformationClinical

  • Drug Fever

    drug-induced fever.

  • Hyperthermia

    an abnormal elevation of body temperature, usually as a result of inability to regulate core body temperature due to non-pathologic factors.

  • Hyperthermia, Induced

    abnormally high temperature intentionally induced in living things regionally or whole body. it is most often induced by radiation (heat waves, infra-red), ultrasound, or drugs.

  • Malignant Hyperthermia

    rapid and excessive rise of temperature accompanied by muscular rigidity following general anesthesia.

  • Phlebovirus

    a genus of the family bunyaviridae comprising many viruses, most of which are transmitted by phlebotomus flies and cause phlebotomus fever. the type species is rift valley fever virus.

  • Severe Fever with Thrombocytopenia Syndrome

    a tick-borne infection with severe fever with thrombocytopenia syndrome bunyavirus of the genus phlebovirus. it is associated with fever, thrombocytopenia; leukocytopenia, and multiorgan dysfunction. it is found in parts of asia including china, japan, korea and vietnam and can be transmitted from infected domestic animals and humans.

  • Sweating Fever

    a febrile response accompanied by diaphoresis.

Patient EducationClinical

Uncommon Infant and Newborn Problems

It can be scary when your baby is sick, especially when it is not an everyday problem like a cold or a fever. You may not know whether the problem is serious or how to treat it. If you have concerns about your baby's health, call your health care provider right away.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert P81.9 to ICD-9-CMHistory

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

ICD-9-CM
778.4 NB temp regulat dis NEC
Approximate The match is approximate rather than exact.

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 P81.9Overview

Is P81.9 (Other disturbances of temperature regulation of newborn) a billable code?

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

What is the ICD-9 equivalent of P81.9?

Under the General Equivalence Mappings, disturbance of temperature regulation of newborn, unspecified converts to ICD-9-CM 778.4 (NB temp regulat dis NEC). The mapping is approximate, so confirm the match fits the documentation.

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.