O09.33 Supervision of pregnancy with insufficient antenatal care, third trimester

Billable ICD-10-CM code, FY2026. Exempt from present-on-admission (POA) reporting.

Applies from O09.3 Supervision of pregnancy with insufficient antenatal care

Applicable to

• Supervision of concealed pregnancy
• Supervision of hidden pregnancy

MS-DRG index

Defines the logic of DRG(s) 998 in MDC 14.

Approximate ICD-9-CM (GEMs)

• V23.7 Supervision of high-risk pregnancy with insufficient prenatal care (approximate)

Medicare Code Edits (MCE v43.1 (April 2026))

• Maternity diagnoses (age 9 through 64): Age conflict edit. These diagnoses are clinically expected only in patients age 9 through 64.
• Unacceptable principal diagnosis: These codes describe a circumstance which influences care but is not a current illness or injury, or capture only an underlying condition, and are unacceptable as principal diagnosis.

Code annotations containing back-references to O09.33

Back-references to O09

• Type 1 Excludes: Z34 Encounter for supervision of normal pregnancy ("encounter for supervision of high risk pregnancy (O09.-)")
• Code First: Z3A Weeks of gestation ("obstetric condition or encounter for delivery (O09-O60, O80-O82, O94-O9A)")

Nearby codes

• O09.299 Supervision of pregnancy with other poor reproductive or obstetric history, unspecified trimester
• O09.3 Supervision of pregnancy with insufficient antenatal care
• O09.30 Supervision of pregnancy with insufficient antenatal care, unspecified trimester
• O09.31 Supervision of pregnancy with insufficient antenatal care, first trimester
• O09.32 Supervision of pregnancy with insufficient antenatal care, second trimester
• O09.33 Supervision of pregnancy with insufficient antenatal care, third trimester (this code)
• O09.4 Supervision of pregnancy with grand multiparity
• O09.40 Supervision of pregnancy with grand multiparity, unspecified trimester
• O09.41 Supervision of pregnancy with grand multiparity, first trimester
• O09.42 Supervision of pregnancy with grand multiparity, second trimester
• O09.43 Supervision of pregnancy with grand multiparity, third trimester