2026 ICD-10-CM Diagnosis Code O33.5XX1Maternal care for disproportion due to unusually large fetus, fetus 1

ICD-10-CM Codes›O00-O9A›O30-O48›O33

ICD-10-CM O33.5XX1
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

O33.5XX1 is a billable ICD-10-CM diagnosis code for maternal care for disproportion due to unusually large fetus, fetus 1. The 7th character 1 identifies fetus 1 in a multiple gestation pregnancy. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 817 through 819, 831 through 833. The code is restricted by the Medicare Code Editor to maternity cases (age 9 through 64). In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Malposition, disproportion or other labor complications.

Code Identity

ICD-10-CM Code
O33.5XX1
Billable Status
Yes — Valid for Submission
Code Describes
Maternal care for disproportion due to unusually large fetus, fetus 1
Short Description
Matern care for disproprtn d/t unusually large fetus, fts1
Parent Code
O33.5
Maternal care for disproportion due to unusually large fetus

Code Classification

ChapterO00-O9APregnancy, childbirth and the puerperium
SectionO30-O48Maternal care related to the fetus and amniotic cavity and possible delivery problems
CategoryO33Maternal care for disproportion
This CodeO33.5XX1Maternal care for disproportion due to unusually large fetus, fetus 1

Code EditsBilling

Medicare Code Editor checks that affect claim validity for O33.5XX1.

Maternity diagnoses
The Medicare Code Editor detects inconsistencies in maternity cases by checking a patient's age and any diagnosis on the patient's record. The maternity code edits apply to patients age ange is 9–64 years inclusive (e.g., diabetes in pregnancy, antepartum pulmonary complication).

Clinical ClassificationClinical

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

CCSR PRG024
Malposition, disproportion or other labor complications
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 O33.5XX1 to ICD-9-CMHistory

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

ICD-9-CM
653.51 Fetal disprop NOS-deliv
Approximate The match is approximate rather than exact.
ICD-9-CM
653.53 Fetal dispro NOS-antepar
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 O33.5XX1Overview

Is O33.5XX1 (Maternal care for disproportion due to unusually large fetus) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report maternal care for disproportion due to unusually large fetus, fetus 1 on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character 1 in O33.5XX1 mean?

The final character 1 identifies the fetus in a multiple gestation pregnancy: this code reports maternal care for disproportion due to unusually large fetus for fetus 1.

What MS-DRG does O33.5XX1 group to?

When maternal care for disproportion due to unusually large fetus, fetus 1 is the principal diagnosis on an inpatient stay, it groups to MS-DRG 817, 818, 819, 831, 832, 833, with relative weights from 0.5229 to 1.6880 depending on complications. Higher weights mean higher Medicare reimbursement.

Who can O33.5XX1 be reported for?

The Medicare Code Editor checks maternal care for disproportion due to unusually large fetus, fetus 1 against patient demographics: this code is intended for maternity cases (age 9 through 64). Claims outside these limits are flagged as inconsistent.

What is the ICD-9 equivalent of O33.5XX1?

Under the General Equivalence Mappings, maternal care for disproportion due to unusually large fetus, fetus 1 converts to ICD-9-CM 653.51 (fetal disprop NOS-deliv) and 653.53 (fetal dispro NOS-antepar). 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.