Weeks of gestation (Z3A) ICD-10-CM
The Z3A code range covers weeks of gestation with 44 ICD-10-CM diagnosis codes. 38 of them are billable and valid for claim submission in fiscal year 2027, and the category headers group them but cannot themselves be billed.
Code First
Certain conditions have both an underlying etiology and multiple body system manifestations due to the underlying etiology. For such conditions, the ICD-10-CM has a coding convention that requires the underlying condition be sequenced first followed by the manifestation. Wherever such a combination exists, there is a "use additional code" note at the etiology code, and a "code first" note at the manifestation code. These instructional notes indicate the proper sequencing order of the codes, etiology followed by manifestation.
- Codes from category Z3A are for use, only on the maternal record, to indicate the weeks of gestation of the pregnancy, if known.
Codes in the Z3A Range 44 codes · 38 billable
- Z3A Weeks of gestationNon-billable
- Z3A.0 Weeks of gestation of pregnancy, unspecified or less than 10 weeksNon-billable
- Z3A.00 Weeks of gestation of pregnancy not specified
- Z3A.01 Less than 8 weeks gestation of pregnancy
- Z3A.08 8 weeks gestation of pregnancy
- Z3A.09 9 weeks gestation of pregnancy
- Z3A.1 Weeks of gestation of pregnancy, weeks 10-19Non-billable
- Z3A.10 10 weeks gestation of pregnancy
- Z3A.11 11 weeks gestation of pregnancy
- Z3A.12 12 weeks gestation of pregnancy
- Z3A.13 13 weeks gestation of pregnancy
- Z3A.14 14 weeks gestation of pregnancy
- Z3A.15 15 weeks gestation of pregnancy
- Z3A.16 16 weeks gestation of pregnancy
- 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 20-29Non-billable
- Z3A.20 20 weeks gestation of pregnancy
- Z3A.21 21 weeks gestation of pregnancy
- 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
- Z3A.27 27 weeks gestation of pregnancy
- Z3A.28 28 weeks gestation of pregnancy
- Z3A.29 29 weeks gestation of pregnancy
- Z3A.3 Weeks of gestation of pregnancy, weeks 30-39Non-billable
- Z3A.30 30 weeks gestation of pregnancy
- Z3A.31 31 weeks gestation of pregnancy
- Z3A.32 32 weeks gestation of pregnancy
- Z3A.33 33 weeks gestation of pregnancy
- Z3A.34 34 weeks gestation of pregnancy
- Z3A.35 35 weeks gestation of pregnancy
- Z3A.36 36 weeks gestation of pregnancy
- Z3A.37 37 weeks gestation of pregnancy
- Z3A.38 38 weeks gestation of pregnancy
- Z3A.39 39 weeks gestation of pregnancy
- Z3A.4 Weeks of gestation of pregnancy, weeks 40 or greaterNon-billable
- Z3A.40 40 weeks gestation of pregnancy
- Z3A.41 41 weeks gestation of pregnancy
- Z3A.42 42 weeks gestation of pregnancy
- Z3A.49 Greater than 42 weeks gestation of pregnancy
About the Z3A Code Range
These codes describe how far along a pregnancy is, expressed in weeks.
Z3A.0 groups pregnancies with an unspecified week or fewer than 10 weeks. Its subdivisions distinguish an unspecified week, less than 8 weeks, 8 weeks, and 9 weeks. Z3A.1, Z3A.2, and Z3A.3 group weeks 10-19, 20-29, and 30-39, respectively, then split by individual week. Z3A.4 groups weeks 40 or greater, distinguishing weeks 40, 41, and 42 from greater than 42 weeks.
Questions About This Page
How many billable codes are in the Z3A range?
Of the 44 codes in this range, 38 are billable and valid for claim submission from October 1, 2026 through September 30, 2027. Category header codes group them but cannot be reported on claims.
What does the Z3A range classify?
The range classifies weeks of gestation. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2027 ICD-10-CM Tabular List and order file, effective October 1, 2026 through September 30, 2027.
