2026 ICD-10-CM Diagnosis Code P07.21Extreme immaturity of newborn, gestational age less than 23 completed weeks
ICD-10-CM Codes›P00–P96›P05-P08›P07
- Billable — Valid for Submission
- Not Chronic
P07.21 is a billable ICD-10-CM diagnosis code for extreme immaturity of newborn, gestational age less than 23 completed weeks. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). Coders also document this condition as baby premature at delivery less than 23 weeks. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Short gestation; low birth weight; and fetal growth retardation.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Baby premature at delivery less than 23 weeks
- Premature baby less than 26 weeks
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Inclusion Terms
- Extreme immaturity of newborn, gestational age less than 23 weeks, 0 days
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
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.
- Immaturity(less than 37 completed weeks)
- extreme of newborn (less than 28 completed weeks of gestation) (less than 196 completed days of gestation) (unspecified weeks of gestation)
- gestational age
- less than 23 completed weeks
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Premature Babies
Almost 1 of every 10 infants born in the United States are premature, or preemies. A premature birth is when a baby is born before 37 completed weeks of pregnancy. A full-term pregnancy is 40 weeks.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert P07.21 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About P07.21Overview
Is P07.21 (Extreme immaturity of newborn) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report extreme immaturity of newborn, gestational age less than 23 completed weeks on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What is the ICD-9 equivalent of P07.21?
Under the General Equivalence Mappings, extreme immaturity of newborn, gestational age less than 23 completed weeks converts to ICD-9-CM 765.21 (<24 comp wks gestation). 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.
