Intrauterine Infection

Intrauterine infection (from Latin intra — within, uterus — uterus, and infectio — infection) is a group of infectious and inflammatory diseases of the fetus resulting from the transmission of a pathogenic microorganism from an infected mother during pregnancy or directly during childbirth.

Etiology and pathophysiology

The principal causative agents of this condition are the TORCH pathogens (Toxoplasma, rubella virus, cytomegalovirus, and herpes simplex virus), as well as syphilis, Zika virus, and parvovirus B19.

The primary route of infection is hematogenous (transplacental). When viremia, bacteremia, or parasitemia develops in a pregnant woman, the pathogen reaches the placenta via the bloodstream, crosses the placental barrier, and enters the fetal circulation.

Pathogenesis and the severity of the lesion depend on the gestational age (stage of pregnancy) at which infection occurred:

• infection in the first and second trimesters (usually before 20 weeks, during embryogenesis and the active development, growth, and maturation of organs and tissues) — leads to massive apoptosis of immature cells and the formation of congenital malformations (teratogenic effect), with consequences of varying severity, often resulting in spontaneous miscarriage, intrauterine fetal death, or fetal growth restriction;
• infection in the third trimester — the organs have already formed, and the risk of congenital malformations is low, but the infection may cause late complications (e.g., psychomotor developmental delay and cognitive impairment).

Clinical Significance

Intrauterine infections are among the leading causes of infant mortality, stillbirth, and severe childhood disability (deafness, blindness, heart defects, and microcephaly).

The difficulty of diagnosis lies in the fact that these infections (e.g., cytomegalovirus infection or toxoplasmosis) are most often asymptomatic or mild in the mother.

Therefore, preconception care (testing for infections before conception) or first-trimester serological screening (ELISA) of all pregnant women is recommended to assess the risk of primary fetal infection.