2026 ICD-10-CM Diagnosis Code O99.320Drug use complicating pregnancy, unspecified trimester

ICD-10-CM Codes›O00-O9A›O94-O9A›O99

ICD-10-CM O99.320
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

O99.320 is a billable ICD-10-CM diagnosis code for drug use 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). Coders also document this condition as drug misuse before confirmation of pregnancy. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified complications in pregnancy and Other specified substance-related disorders.

Code Identity

ICD-10-CM Code
O99.320
Billable Status
Yes — Valid for Submission
Code Describes
Drug use complicating pregnancy, unspecified trimester
Short Description
Drug use complicating pregnancy, unspecified trimester
Same as the full description in the CMS dataset.
Parent Code
O99.32
Drug use 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 CodeO99.320Drug use complicating pregnancy, unspecified trimester

Code EditsBilling

Medicare Code Editor checks that affect claim validity for O99.320.

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.

  • Drug misuse before confirmation of pregnancy
  • Maternal drug exposure
  • Maternal drug use
  • Pregnancy and substance dependence
  • Prenatal finding
  • Substance dependence during pregnancy, childbirth and/or puerperium
  • Substance dependence in mother complicating pregnancy, childbirth and/or puerperium

Clinical ClassificationClinical

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

CCSR PRG028
Other specified complications in pregnancy
Default principal diagnosis: inpatient Yes · outpatient Yes
CCSR MBD025
Other specified substance-related disorders
Default principal diagnosis: inpatient No · outpatient No

Patient EducationClinical

Pregnancy and Substance Use

During pregnancy, there are many things you can do to keep yourself and your baby healthy. They include getting regular prenatal care, eating healthy, and staying active. But it's also very important to avoid substances that could be harmful to you and your baby, such as tobacco, alcohol, and drugs.

Read the full article at MedlinePlus

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

Convert O99.320 to ICD-9-CMHistory

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

ICD-9-CM
648.30 Drug depend 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 O99.320Overview

Is O99.320 a billable code?

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

What MS-DRG does O99.320 group to?

When drug use 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 O99.320 be reported for?

The Medicare Code Editor checks drug use 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 O99.320?

Under the General Equivalence Mappings, drug use complicating pregnancy, unspecified trimester converts to ICD-9-CM 648.30 (drug depend 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.