2026 ICD-10-CM Diagnosis Code O30.029Conjoined twin pregnancy, unspecified trimester

ICD-10-CM Codes›O00-O9A›O30-O48›O30

ICD-10-CM O30.029
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

O30.029 is a billable ICD-10-CM diagnosis code for conjoined twin pregnancy, unspecified trimester. 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). Coders also document this condition as conjoined twin pregnancy. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Multiple gestation.

Code Identity

ICD-10-CM Code
O30.029
Billable Status
Yes — Valid for Submission
Code Describes
Conjoined twin pregnancy, unspecified trimester
Short Description
Conjoined twin pregnancy, unspecified trimester
Same as the full description in the CMS dataset.
Parent Code
O30.02
Conjoined twin pregnancy

Code Classification

ChapterO00-O9APregnancy, childbirth and the puerperium
SectionO30-O48Maternal care related to the fetus and amniotic cavity and possible delivery problems
CategoryO30Multiple gestation
This CodeO30.029Conjoined twin pregnancy, unspecified trimester

Code EditsBilling

Medicare Code Editor checks that affect claim validity for O30.029.

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).

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Conjoined twin pregnancy
  • Disproportion between fetus and pelvis
  • Disproportion between fetus and pelvis due to conjoined twins

Clinical ClassificationClinical

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

CCSR PRG012
Multiple gestation
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Twins, Triplets, Multiple Births

If you are pregnant with more than one baby, you are far from alone. Multiple births are up in the United States. More women are having babies after age 30 and more are taking fertility drugs. Both boost the chance of carrying more than one baby. A family history of twins also makes multiples more likely.

Read the full article at MedlinePlus

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

Convert O30.029 to ICD-9-CMHistory

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

ICD-9-CM
678.10 Fetal conjoin twins-unsp
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 O30.029Overview

Is O30.029 (Conjoined twin pregnancy) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report conjoined twin pregnancy, unspecified trimester on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does O30.029 group to?

When conjoined twin pregnancy, unspecified trimester 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 O30.029 be reported for?

The Medicare Code Editor checks conjoined twin pregnancy, unspecified trimester 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 O30.029?

Under the General Equivalence Mappings, conjoined twin pregnancy, unspecified trimester converts to ICD-9-CM 678.10 (fetal conjoin twins-unsp). 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.