2026 ICD-10-CM Diagnosis Code O99.012Anemia complicating pregnancy, second trimester

ICD-10-CM Codes›O00-O9A›O94-O9A›O99

ICD-10-CM O99.012
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

O99.012 is a billable ICD-10-CM diagnosis code for anemia complicating pregnancy, second 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 Other specified complications in pregnancy.

Code Identity

ICD-10-CM Code
O99.012
Billable Status
Yes — Valid for Submission
Code Describes
Anemia complicating pregnancy, second trimester
Short Description
Anemia complicating pregnancy, second trimester
Same as the full description in the CMS dataset.
Parent Code
O99.01
Anemia complicating pregnancy

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 CodeO99.012Anemia complicating pregnancy, second trimester

Code EditsBilling

Medicare Code Editor checks that affect claim validity for O99.012.

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 PRG028
Other specified complications in pregnancy
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Anemia

If you have anemia, your blood does not carry enough oxygen to the rest of your body. The most common cause of anemia is not having enough iron. Your body needs iron to make hemoglobin. Hemoglobin is an iron-rich protein that gives the red color to blood. It carries oxygen from the lungs to the rest of the body.

Read the full article at MedlinePlus

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

Convert O99.012 to ICD-9-CMHistory

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

ICD-9-CM
648.21 Anemia-delivered
Approximate The match is approximate rather than exact.
ICD-9-CM
648.23 Anemia-antepartum
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 O99.012Overview

Is O99.012 (Anemia complicating pregnancy) a billable code?

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

What MS-DRG does O99.012 group to?

When anemia complicating pregnancy, second 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 O99.012 be reported for?

The Medicare Code Editor checks anemia complicating pregnancy, second 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 O99.012?

Under the General Equivalence Mappings, anemia complicating pregnancy, second trimester converts to ICD-9-CM 648.21 (anemia-delivered) and 648.23 (anemia-antepartum). 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.