2026 ICD-10-CM Diagnosis Code O99.340Other mental disorders complicating pregnancy, unspecified trimester

ICD-10-CM Codes›O00-O9A›O94-O9A›O99

ICD-10-CM O99.340
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

O99.340 is a billable ICD-10-CM diagnosis code for other mental disorders complicating 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). In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Miscellaneous mental and behavioral disorders/conditions and Other specified complications in pregnancy.

Code Identity

ICD-10-CM Code
O99.340
Billable Status
Yes — Valid for Submission
Code Describes
Other mental disorders complicating pregnancy, unspecified trimester
Short Description
Oth mental disorders complicating pregnancy, unsp trimester
Parent Code
O99.34
Other mental disorders complicating pregnancy, childbirth, and the puerperium

Code Classification

ChapterO00-O9APregnancy, childbirth and the puerperium
SectionO94-O9AOther obstetric conditions, not elsewhere classified
CategoryO99Other maternal diseases classifiable elsewhere but complicating pregnancy, childbirth and the puerperium
This CodeO99.340Other mental disorders complicating pregnancy, unspecified trimester

Code EditsBilling

Medicare Code Editor checks that affect claim validity for O99.340.

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.

  • Adjustment disorder during pregnancy
  • Antenatal depression
  • Anxiety disorder in pregnancy
  • Anxiety in pregnancy
  • Depressive disorder in mother complicating pregnancy
  • Major depressive disorder in mother complicating pregnancy
  • Mental disorder in mother complicating pregnancy
  • Mental disorders during pregnancy, childbirth and the puerperium
  • Mood disorder during pregnancy
  • Psychological disorder during pregnancy
  • Psychotic disorder in mother complicating pregnancy

Clinical ClassificationClinical

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

CCSR MBD013
Miscellaneous mental and behavioral disorders/conditions
Default principal diagnosis: inpatient No · outpatient No
CCSR PRG028
Other specified complications in pregnancy
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Health Problems in Pregnancy

A health problem in pregnancy is any disease or condition that could affect your health or the health of your fetus. Some health problems may make it more likely that you will have a high-risk pregnancy. A high-risk pregnancy is one in which you, your fetus, or both are at higher risk for health problems than in a typical pregnancy.

The full article covers:

  • What are health problems in pregnancy?
  • What raises my risk for health problems during pregnancy?
  • Can chronic health conditions cause problems in pregnancy?
  • Can health problems in pregnancy be prevented?

Read the full article at MedlinePlus

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

Convert O99.340 to ICD-9-CMHistory

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

ICD-9-CM
648.40 Mental dis preg-unspec
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 O99.340Overview

Is O99.340 a billable code?

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

What MS-DRG does O99.340 group to?

When other mental disorders complicating 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 O99.340 be reported for?

The Medicare Code Editor checks other mental disorders complicating 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 O99.340?

Under the General Equivalence Mappings, other mental disorders complicating pregnancy, unspecified trimester converts to ICD-9-CM 648.40 (mental dis preg-unspec). 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.