O91
Infections of breast associated with pregnancy, the puerperium and lactation
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This code does not map to a risk-adjusting HCC in the loaded models.
Coding notes
Excludes 1 never coded together · Excludes 2 may co-exist
code to identify infection
supervision of normal pregnancy (Z34.-)
mental and behavioral disorders associated with the puerperium (F53.-) obstetrical tetanus (A34) postpartum necrosis of pituitary gland (E23.0) puerperal osteomalacia (M83.0)
code, if applicable, from category Z3A, Weeks of gestation, to identify the specific week of the pregnancy, if known.
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
Official Guidelines for O91
FY 2026 ›Subsections
- I.C.15.aGeneral Rules for Obstetric Cases
- I.C.15.bSelection of OB Principal or First-listed Diagnosis
- I.C.15.cPre-existing conditions versus conditions due to the pregnancy
- I.C.15.dPre-existing hypertension in pregnancy
- I.C.15.eFetal Conditions Affecting the Management of the Mother
- I.C.15.fHIV Infection in Pregnancy, Childbirth and the Puerperium
- I.C.15.gDiabetes mellitus in pregnancy
- I.C.15.hLong term use of insulin and oral hypoglycemics
- I.C.15.iGestational (pregnancy induced) diabetes
- I.C.15.jSepsis and septic shock complicating abortion, pregnancy, childbirth and the puerperium
- I.C.15.kPuerperal sepsis
- I.C.15.lAlcohol, tobacco and drug use during pregnancy, childbirth and the puerperium
- I.C.15.mPoisoning, toxic effects, adverse effects and underdosing in a pregnant patient
- I.C.15.nNormal Delivery, Code O80
- I.C.15.oThe Peripartum and Postpartum Periods
- I.C.15.pCode O94, Sequelae of complication of pregnancy, childbirth, and the puerperium
- I.C.15.qTermination of Pregnancy and Spontaneous abortions
- I.C.15.rAbuse in a pregnant patient
- I.C.15.sCOVID-19 infection in pregnancy, childbirth, and the puerperium
Sections that reference O91
Sections whose FY 2026 text names O91, its O91 category, or a range containing it — the chapter guidance above is the authoritative source.