O36.5121 Maternal care for known or suspected placental insufficiency, second trimester, fetus 1

Billable ICD-10-CM code, FY2026.

Built from O36.512 with 7th character 1 (fetus 1).

Applies from O36 Maternal care for other fetal problems

Includes

• the listed conditions in the fetus as a reason for hospitalization or other obstetric care of the mother, or for termination of pregnancy

Excludes1 (never code together)

• encounter for suspected maternal and fetal conditions ruled out (Z03.7-)
• placental transfusion syndromes (O43.0-)

Excludes2 (not included here)

• labor and delivery complicated by fetal stress (O77.-)

7th character note

• One of the following 7th characters is to be assigned to each code under category O36. 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 O36 that has a 7th character of 1 through 9.

7th character required

• 0 — not applicable or unspecified
• 1 — fetus 1
• 2 — fetus 2
• 3 — fetus 3
• 4 — fetus 4
• 5 — fetus 5
• 9 — other fetus

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.

Code annotations containing back-references to O36.5121

Back-references to O36.5

• Type 2 Excludes: O43 Placental disorders ("maternal care for poor fetal growth due to placental insufficiency (O36.5-)")

Back-references to O36

• Type 2 Excludes: O98 Maternal infectious and parasitic diseases classifiable elsewhere but complicating pregnancy, childbirth and the puerperium ("when the reason for maternal care is that the disease is known or suspected to have affected the fetus (O35-O36)")
• Type 2 Excludes: O99 Other maternal diseases classifiable elsewhere but complicating pregnancy, childbirth and the puerperium ("when the reason for maternal care is that the condition is known or suspected to have affected the fetus (O35-O36)")
• Type 1 Excludes: Z03.7 Encounter for suspected maternal and fetal conditions ruled out ("known or suspected fetal anomalies affecting management of mother, not ruled out (O26.-, O35.-, O36.-, O40.-, O41.-)")

Nearby codes

• O36.5114 Maternal care for known or suspected placental insufficiency, first trimester, fetus 4
• O36.5115 Maternal care for known or suspected placental insufficiency, first trimester, fetus 5
• O36.5119 Maternal care for known or suspected placental insufficiency, first trimester, other fetus
• O36.512 Maternal care for known or suspected placental insufficiency, second trimester
• O36.5120 Maternal care for known or suspected placental insufficiency, second trimester, not applicable or unspecified
• O36.5121 Maternal care for known or suspected placental insufficiency, second trimester, fetus 1 (this code)
• O36.5122 Maternal care for known or suspected placental insufficiency, second trimester, fetus 2
• O36.5123 Maternal care for known or suspected placental insufficiency, second trimester, fetus 3
• O36.5124 Maternal care for known or suspected placental insufficiency, second trimester, fetus 4
• O36.5125 Maternal care for known or suspected placental insufficiency, second trimester, fetus 5
• O36.5129 Maternal care for known or suspected placental insufficiency, second trimester, other fetus