O98.913 Unspecified maternal infectious and parasitic disease complicating pregnancy, third trimester

Billable ICD-10-CM code, FY2026. Acts as a Complication or Comorbidity (CC) as a secondary diagnosis.

Applies from O98 Maternal infectious and parasitic diseases classifiable elsewhere but complicating pregnancy, childbirth and the puerperium

Includes

• the listed conditions when complicating the pregnant state, when aggravated by the pregnancy, or as a reason for obstetric care

Excludes2 (not included here)

• herpes gestationis (O26.4-)
• infectious carrier state (O99.82-, O99.83-)
• obstetrical tetanus (A34)
• puerperal infection (O86.-)
• puerperal sepsis (O85)
• when the reason for maternal care is that the disease is known or suspected to have affected the fetus (O35-O36)

Use additional code

• code (Chapter 1), to identify specific infectious or parasitic disease

MS-DRG index

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

Approximate ICD-9-CM (GEMs)

• 647.91 Unspecified infection or infestation of mother, delivered, with or without mention of antepartum condition (approximate)
• 647.93 Unspecified infection or infestation of mother, 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.

Nearby codes

• O98.83 Other maternal infectious and parasitic diseases complicating the puerperium
• O98.9 Unspecified maternal infectious and parasitic disease complicating pregnancy, childbirth and the puerperium
• O98.91 Unspecified maternal infectious and parasitic disease complicating pregnancy
• O98.911 Unspecified maternal infectious and parasitic disease complicating pregnancy, first trimester
• O98.912 Unspecified maternal infectious and parasitic disease complicating pregnancy, second trimester
• O98.913 Unspecified maternal infectious and parasitic disease complicating pregnancy, third trimester (this code)
• O98.919 Unspecified maternal infectious and parasitic disease complicating pregnancy, unspecified trimester
• O98.92 Unspecified maternal infectious and parasitic disease complicating childbirth
• O98.93 Unspecified maternal infectious and parasitic disease complicating the puerperium