2027 ICD-10-CM Diagnosis Code O26.12Low weight gain in pregnancy, second trimester
ICD-10-CM Codes›O00-O9A›O20-O29›O26
- Billable — Valid for Submission
- Not Chronic
O26.12 is a billable ICD-10-CM diagnosis code for low weight gain in pregnancy, second trimester. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) 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.
This medical diagnosis code is frequently used in OB/GYN medical specialties to designate conditions such maternal disorders related to pregnancy.
Code Identity
Code Classification
Code EditsBilling
Medicare Code Editor checks that affect claim validity for O26.12.
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to O26.12: its own notes plus those printed at block O20-O29 and 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.
- 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.
Use Additional Code
Add a second code, after this one, to fully describe the condition.
- 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.
- 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 O26.12, its category, or a range that includes it.
Excludes1 1
These codes carry an Excludes1 note naming O26.12: they are not reported together with it, unless the two conditions are unrelated.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Low Weight Gain in Pregnancy
in a woman with a normal weight pre-pregnancy body mass index (bmi), i.e. 18.5-24.9, the weight gained during pregnancy does not exceed a total weight gain of 25 lbs. in a woman with an underweight pre-pregnancy body mass index (bmi), i.e. less than 18.5, the weight gained during pregnancy does not exceed a total weight gain of 28 lbs. in a woman with an overweight pre-pregnancy body mass index (bmi), i.e. 25.0-29.9, the weight gained during pregnancy does not exceed a total weight gain of 15 lbs. in a woman with an obese pre-pregnancy body mass index (bmi), i.e. greater than 30, the weight gained during pregnancy does not exceed a total weight gain of 11 lbs. these standards are supported for the whole population irrespective of height, race or ethnicity.
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 O26.12 to ICD-9-CMHistory
Code HistoryHistory
Questions About O26.12Overview
What is the ICD-10 code for low weight gain in pregnancy, second trimester?
The ICD-10-CM code for low weight gain in pregnancy, second trimester is O26.12 (sometimes written as O2612). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is O26.12 (Low weight gain in pregnancy) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report low weight gain in pregnancy, second trimester on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does O26.12 group to?
When low weight gain in pregnancy, second trimester is the principal diagnosis on an inpatient stay, it groups to MS-DRG 833, 832, 831, 819, 818, 817, with relative weights from 0.5000 to 1.7586 depending on complications. Higher weights mean higher Medicare reimbursement.
Who can O26.12 be reported for?
The Medicare Code Editor checks low weight gain in 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 O26.12?
Under the General Equivalence Mappings, low weight gain in pregnancy, second trimester converts to ICD-9-CM 646.81 (preg compl NEC-delivered) and 646.83 (preg compl NEC-antepart). The mapping is approximate, so confirm the match fits the documentation.
