O35.1
Maternal care for (suspected) chromosomal abnormality in fetus
O35.1 is a non-billable ICD-10-CM code header for maternal care for (suspected) chromosomal abnormality in fetus. Report a more specific code from it instead. It is part of the FY2027 code set, effective October 1, 2026. The more specific codes under it are O35.10 Maternal care for (suspected) chromosomal abnormality in fetus, unspecified; O35.11 Maternal care for (suspected) chromosomal abnormality in fetus, Trisomy 13; O35.12 Maternal care for (suspected) chromosomal abnormality in fetus, Trisomy 18; O35.13 Maternal care for (suspected) chromosomal abnormality in fetus, Trisomy 21 and 3 more. Its coding notes include a Use additional code instruction, a Code also instruction, 2 Excludes1 entries and 4 Excludes2 entries.
7th characters
Every code below needs one of these (defined at O35).
One of the following 7th characters is to be assigned to each code under category O35. 7th character 0 is for single gestations and multiple gestations where the fetus is unspecified. 7th characters 1 through 9 are for cases of multiple gestations to identify the fetus for which the code applies. The appropriate code from category O30, Multiple gestation, must also be assigned when assigning a code from category O35 that has a 7th character of 1 through 9.
- 0not applicable or unspecified
- 1fetus 1
- 2fetus 2
- 3fetus 3
- 4fetus 4
- 5fetus 5
- 9other fetus
Guidelines tip
From the FY2027 Official Guidelines. ICD10Ref adds no rules of its own.
The trimester character comes from the provider's documentation for the current encounter. The unspecified trimester code should rarely be used.
Use additional code
Add the listed code as a secondary code, if known.
Also from chapter/block level (1 note)
- code, if applicable, from category Z3A, Weeks of gestation, to identify the specific week of the pregnancy, if known.
Code also
Two codes may be needed to describe the condition. This note gives no sequencing order.
- any associated maternal condition
Excludes1
Not coded here. The listed conditions generally should not be reported together.
- encounter for suspected maternal and fetal conditions ruled out (Z03.7-)
Also from chapter/block level (1 note)
- supervision of normal pregnancy (Z34.-)
Excludes2
Not included here. Both codes may be reported if the patient has both conditions.
Also from chapter/block level (4 notes)
Includes
Further defines or gives examples of the content of the category.
- the listed conditions in the fetus as a reason for hospitalization or other obstetric care to the mother, or for termination of pregnancy
Notes
Also from chapter/block level (6 notes)
- CODES FROM THIS CHAPTER ARE FOR USE ONLY ON MATERNAL RECORDS, NEVER ON NEWBORN RECORDS
- Codes from this chapter are for use for conditions related to or aggravated by the pregnancy, childbirth, or by the puerperium (maternal causes or obstetric causes)
- Trimesters are counted from the first day of the last menstrual period. They are defined as follows:
- 1st trimester- less than 14 weeks 0 days
- 2nd trimester- 14 weeks 0 days to less than 28 weeks 0 days
- 3rd trimester- 28 weeks 0 days until delivery
More specific codes under O35.1 7
- O35.10Maternal care for (suspected) chromosomal abnormality in fetus, unspecified7th char needed
- O35.11Maternal care for (suspected) chromosomal abnormality in fetus, Trisomy 137th char needed
- O35.12Maternal care for (suspected) chromosomal abnormality in fetus, Trisomy 187th char needed
- O35.13Maternal care for (suspected) chromosomal abnormality in fetus, Trisomy 217th char needed
- O35.14Maternal care for (suspected) chromosomal abnormality in fetus, Turner Syndrome7th char needed
- O35.15Maternal care for (suspected) chromosomal abnormality in fetus, sex chromosome abnormality7th char needed
- O35.19Maternal care for (suspected) chromosomal abnormality in fetus, other chromosomal abnormality7th char needed