P04.9
BillableNewborn affected by maternal noxious substance, unspecified
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is P04.9 an HCC code?
Yes. P04.9 maps to Drug Use Disorder/Substance Use Disorder, Moderate/Severe under the CMS-HCC V28 risk adjustment model.
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for P04.9
For P04.9to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically — it has to be re-documented and supported each calendar year.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed P04.9 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
P04.9 is the ICD-10-CM diagnosis code for newborn affected by maternal noxious substance, unspecified. A newborn affected by a maternal noxious substance during pregnancy, but the specific substance is not identified or documented. P04.9 sits in the ICD-10-CM chapter for certain conditions originating in the perinatal period (p00-p96), within the section covering newborn affected by maternal factors and by complications of pregnancy, labor, and delivery (p00-p04).
Under the CMS-HCC V28 risk adjustment model, P04.9 maps to Drug Use Disorder/Substance Use Disorder, Moderate/Severe (HCC 137) with a community, non-dual, aged base RAF weight of 0.358. P04.9 was not retained as a payment HCC under the older V24 model, so V28 introduced or recategorized it during the 2024–2026 phase-in. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
This is a non-specific code; attempt to identify the actual substance and use a more specific P04 code when possible. Because P04.9 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for P04.9 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This is a non-specific code; attempt to identify the actual substance and use a more specific P04 code when possible
- •Use only when documentation is insufficient to determine the type of maternal noxious substance
Clinical Significance
Newborn effects from unspecified maternal noxious substances indicate potential toxic exposure where the specific agent is unknown or undocumented. These cases require systematic evaluation to identify possible substance-related effects and establish appropriate monitoring protocols.
Documentation Requirements
- ✓Documentation that newborn is affected by noxious substance
- ✓Clinical signs suggesting toxic exposure
- ✓History of potential maternal exposures
- ✓Attempts to identify specific substances if possible
- ✓Organ system assessments for toxic effects
- ✓Laboratory studies as clinically indicated
- ✓Safety assessment and environmental evaluation