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 2026, 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
Clinical Terms in This Code Range
Definitions from the National Library of Medicine for conditions coded in the Z3A range.
Hypercapnia
A clinical manifestation of abnormal increase in the amount of carbon dioxide in arterial blood.
Restless Legs Syndrome
A disorder characterized by aching or burning sensations in the lower and rarely the upper extremities that occur prior to sleep or may awaken the patient from sleep.
About the Z3A Code Range
The Z3A ICD-10 code section is used to specify the exact weeks of gestation during a pregnancy. These codes help record the precise stage of pregnancy, ranging from less than 8 weeks to greater than 42 weeks gestation.
This section includes detailed codes, such as Z3A.01 for pregnancies under 8 weeks, Z3A.19 for 19 weeks, up through Z3A.42 for 42 weeks, and beyond with Z3A.49 indicating greater than 42 weeks gestation. Coders can select specific codes that correlate with gestational age synonyms like “gestation period 10 weeks” or “gestation less than 20 weeks.” Notably, the Z3A.00 code covers unspecified gestational weeks and includes related fetal disorder conditions due to maternal health factors. These precise week-based codes are critical for documenting pregnancy progress in medical records, enabling appropriate prenatal care and monitoring. Understanding the ICD-10 code for weeks of gestation allows both healthcare professionals and coders to convey the pregnancy timeline accurately and consistently.
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, 2025 through September 30, 2026. 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 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
