2027 ICD-10-CM Diagnosis Code O16Unspecified maternal hypertension

ICD-10-CM Codes›O00-O9A›O10-O16›O16

ICD-10-CM O16
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

O16 is a non-billable ICD-10-CM category code for unspecified maternal hypertension, so it cannot be submitted on claims. Use a more specific code from this category instead, such as O16.1, O16.2, O16.3, and O16.4.

Code Identity

ICD-10-CM Code
O16
Billable Status
No — Non-Billable Category
Code Describes
Unspecified maternal hypertension
Short Description
Unspecified maternal hypertension
Same as the full description in the CMS dataset.
Chapter
O10-O16
Edema, proteinuria and hypertensive disorders in pregnancy, childbirth and the puerperium

Code Classification

ChapterO00-O9APregnancy, childbirth and the puerperium
SectionO10-O16Edema, proteinuria and hypertensive disorders in pregnancy, childbirth and the puerperium
CategoryO16Unspecified maternal hypertension
This CodeO16Unspecified maternal hypertension

Specific Coding for Unspecified maternal hypertensionOverview

Non-specific codes like O16 require more characters. Use one of these billable codes instead:

  • Use O16.1 for Unspecified maternal hypertension, first trimester

  • Use O16.2 for Unspecified maternal hypertension, second trimester

  • Use O16.3 for Unspecified maternal hypertension, third trimester

  • Use O16.4 for Unspecified maternal hypertension, complicating childbirth

  • Use O16.5 for Unspecified maternal hypertension, complicating the puerperium

  • Use O16.9 for Unspecified maternal hypertension, unspecified trimester

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to O16: its own notes plus those printed at Chapter 15. A note printed at a category, block or chapter applies to every code under it.

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From Chapter 15 (O00-O9A) Pregnancy, childbirth and the puerperium applies to 2,481 codes
  • supervision of normal pregnancy (Z34.-)

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Chapter 15 (O00-O9A) Pregnancy, childbirth and the puerperium applies to 2,481 codes
  • mental and behavioral disorders associated with the puerperium (F53.-)
  • obstetrical tetanus (A34)
  • postpartum necrosis of pituitary gland (E23.0)
  • puerperal osteomalacia (M83.0)

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From Chapter 15 (O00-O9A) Pregnancy, childbirth and the puerperium applies to 2,481 codes
  • code, if applicable, from category Z3A, Weeks of gestation, to identify the specific week of the pregnancy, if known.

Notes

General instructions on how these codes are used.

From Chapter 15 (O00-O9A) Pregnancy, childbirth and the puerperium applies to 2,481 codes
  • CODES FROM THIS CHAPTER ARE FOR USE ONLY ON MATERNAL RECORDS, NEVER ON NEWBORN RECORDS
  • Codes from this chapter are for use for conditions related to or aggravated by the pregnancy, childbirth, or by the puerperium (maternal causes or obstetric causes)
  • Trimesters are counted from the first day of the last menstrual period. They are defined as follows:
  • 1st trimester- less than 14 weeks 0 days
  • 2nd trimester- 14 weeks 0 days to less than 28 weeks 0 days
  • 3rd trimester- 28 weeks 0 days until delivery

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name O16, its category, or a range that includes it.

Includes 1

These notes mention O16.

  • O15 Eclampsia
    convulsions following conditions in O10-O14 and O16

Applicable To 1

These notes mention O16.

  • P00.0 Newborn affected by maternal hypertensive disorders
    Newborn affected by maternal conditions classifiable to O10-O11, O13-O16 names O13-O16, which includes this code

Excludes1 1

These codes carry an Excludes1 note naming O16: they are not reported together with it, unless the two conditions are unrelated.

  • I10 Essential (primary) hypertension
    hypertensive disease complicating pregnancy, childbirth and the puerperium (O10-O11, O13-O16) names O13-O16, which includes this code

Excludes2 2

These codes carry an Excludes2 note naming O16: its condition is not part of those codes, and both may be reported when the patient has both.

  • Block I10-I1A Hypertensive diseases
    hypertensive disease complicating pregnancy, childbirth and the puerperium (O10-O11, O13-O16) names O13-O16, which includes this code
  • O99.4 Diseases of the circulatory system complicating pregnancy, childbirth and the puerperium
    hypertensive disorders (O10-O16) names O10-O16, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Patient EducationClinical

High Blood Pressure in Pregnancy

Blood pressure is the force of your blood pushing against the walls of your arteries. Your arteries are blood vessels that carry blood from your heart to other parts of your body. High blood pressure, or hypertension, is blood pressure that is higher than normal.

The full article covers:

  • What is high blood pressure in pregnancy?
  • What are the types of high blood pressure in pregnancy?
  • Who is more likely to develop high blood pressure in pregnancy?
  • What are the symptoms of high blood pressure in pregnancy?
  • What problems can high blood pressure in pregnancy cause?
  • How is high blood pressure in pregnancy diagnosed?
  • What are the treatments for high blood pressure in pregnancy?

Read the full article at MedlinePlus

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

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About O16Overview

What is the ICD-10 code for unspecified maternal hypertension?

O16 is the ICD-10-CM category for unspecified maternal hypertension, but it is a non-billable header: claims need a more specific code from this category, listed on this page.

Is O16 (Unspecified maternal hypertension) a billable code?

No. This is a category header that groups the codes for unspecified maternal hypertension, and headers cannot be submitted on claims. Claims for unspecified maternal hypertension need a more specific code from this category, such as O16.1, O16.2, and O16.3.