Z3A.21 21 weeks gestation of pregnancy

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

Applies from Z3A Weeks of gestation

Code first

• obstetric condition or encounter for delivery (O09-O60, O80-O82, O94-O9A)

Notes

• Codes from category Z3A are for use, only on the maternal record, to indicate the weeks of gestation of the pregnancy, if known.

MS-DRG index

Defines the logic of DRG(s) 951 in MDC 23.

Approximate ICD-9-CM (GEMs)

• NoD.x (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.

Diagnosis Index entries for Z3A.21

• Pregnancy (single) (uterine) › weeks of gestation › 21 weeks

Nearby codes

• Z3A.17 17 weeks gestation of pregnancy
• Z3A.18 18 weeks gestation of pregnancy
• Z3A.19 19 weeks gestation of pregnancy
• Z3A.2 Weeks of gestation of pregnancy, weeks 20-29
• Z3A.20 20 weeks gestation of pregnancy
• Z3A.21 21 weeks gestation of pregnancy (this code)
• Z3A.22 22 weeks gestation of pregnancy
• Z3A.23 23 weeks gestation of pregnancy
• Z3A.24 24 weeks gestation of pregnancy
• Z3A.25 25 weeks gestation of pregnancy
• Z3A.26 26 weeks gestation of pregnancy