O26.01 Excessive weight gain in pregnancy, first trimester

Billable ICD-10-CM code, FY2026.

Applies from O26.0 Excessive weight gain in pregnancy

Excludes2 (not included here)

• gestational edema (O12.0, O12.2)

MS-DRG index

Defines the logic of DRG(s) 817-819 in MDC 14.

Approximate ICD-9-CM (GEMs)

• 646.11 Edema or excessive weight gain in pregnancy, without mention of hypertension, delivered, with or without mention of antepartum complication (approximate)
• 646.13 Edema or excessive weight gain in pregnancy, without mention of hypertension, antepartum condition or complication (approximate)

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 O26.01

Back-references to O26.0

• Type 1 Excludes: R63.5 Abnormal weight gain ("excessive weight gain in pregnancy (O26.0-)")

Back-references to O26

• 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

• O26 Maternal care for other conditions predominantly related to pregnancy
• O26.0 Excessive weight gain in pregnancy
• O26.00 Excessive weight gain in pregnancy, unspecified trimester
• O26.01 Excessive weight gain in pregnancy, first trimester (this code)
• O26.02 Excessive weight gain in pregnancy, second trimester
• O26.03 Excessive weight gain in pregnancy, third trimester
• O26.1 Low weight gain in pregnancy
• O26.10 Low weight gain in pregnancy, unspecified trimester
• O26.11 Low weight gain in pregnancy, first trimester