O21.0 ICD-10-CA subcategory: Mild hyperemesis gravidarum
O21.0 isn’t a code on its own. Choose one of the 3 codes beneath it, the one the documentation supports.
Official description
O21.0Mild hyperemesis gravidarum
ICD-10-CA · Canada · Also written O210
Codes in O21.0
O21.0 isn’t a code on its own. Open the code that matches what the note documents.
Notes for O21.0
As CIHI prints them, with any note O21.0 takes from the headings above it.
Includes
- • Hyperemesis gravidarum, mild or unspecified, starting before the end of the 22nd week of gestation
Use additional code
Add a code for this detail when the note documents it.
- Use additional code to identify cause.From O21 Excessive vomiting in pregnancy
Excludes
Conditions classified elsewhere.
- Maternal:• care related to the fetus and amniotic cavity and possible delivery problems (O30-O48)• diseases classifiable elsewhere but complicating pregnancy, labour and delivery, and the puerperium (O98-O99)From O20-O29 Other maternal disorders predominantly related to pregnancy
- Certain diseases or injuries complicating pregnancy, childbirth, and the puerperium classified elsewhere:external causes (for mortality) (V,W,X,Y)injury, poisoning and certain other consequences of external causes (S00-T88.1, T88.6-T98)mental and behavioural disorders associated with the puerperium (F53.-)obstetrical tetanus (A34)postpartum necrosis of pituitary gland (E23.0)puerperal osteomalacia (M83.0)supervision of:• high-risk pregnancy (Z35.-)• normal pregnancy (Z34.-)From Chapter 15: Pregnancy, childbirth and the puerperium (O00-O99)
Note
- Categories O24.- and O25.- include the listed conditions even if they occur during childbirth or the puerperium.From O20-O29 Other maternal disorders predominantly related to pregnancy
- The codes included in this chapter are to be used for conditions related to or aggravated by the pregnancy, childbirth or by the puerperium (maternal causes or obstetric causes)From Chapter 15: Pregnancy, childbirth and the puerperium (O00-O99)
Where O21.0 sits
- 1ChapterChapter 15: Pregnancy, childbirth and the puerperium (O00-O99)
- 2Block O20-O29Other maternal disorders predominantly related to pregnancy
- 3Category O21Excessive vomiting in pregnancy
- 4Subcategory O21.0Mild hyperemesis gravidarum
Source and release
- Data release
- ICD-10-CA · FY 2026–2027
- Effective date
- Apr 1, 2026
- Publisher
- CIHI
This page is built from the ICD-10-CA catalog that Vero Codes reads when it suggests codes: Canadian Institute for Health Information’s FY 2026–2027 release, imported from the publisher’s file and checked against it. The description, notes and structured data come from the same record.
Frequently asked questions
Is O21.0 a valid ICD-10-CA code?
No. O21.0 (Mild hyperemesis gravidarum) is a subcategory heading in CIHI’s ICD-10-CA FY 2026–2027 release. It holds 3 codes; record the one the documentation supports.
Where is O21.0 in ICD-10-CA?
O21.0 sits under O21 Excessive vomiting in pregnancy, within O20-O29 Other maternal disorders predominantly related to pregnancy, within Chapter 15: Pregnancy, childbirth and the puerperium (O00-O99).
What coding notes apply to O21.0?
ICD-10-CA lists Includes, Use additional code, Note, Excludes notes for O21.0, including those from the headings it sits under. They are listed on this page with where each one comes from.
Which ICD-10-CA release does this page use?
It uses CIHI’s FY 2026–2027 release, in effect from Apr 1, 2026 to Mar 31, 2027. It is a reference: confirm the code against the current list and the payer’s rules before you submit it.