Can toxoplasmosis cause early miscarriage?

Can Toxoplasmosis Cause Early Miscarriage?

Yes, toxoplasmosis acquired during early pregnancy can cause miscarriage, though the risk is relatively low when infection occurs in the first trimester, with transmission rates of only 2-15% and most severe outcomes occurring when infection happens early in gestation. 1, 2, 3

Risk of Transmission and Miscarriage by Gestational Age

The timing of maternal infection critically determines both transmission risk and pregnancy outcomes:

• First trimester (≤13 weeks): Transmission risk is lowest at 2-15%, but when fetal infection does occur, it results in the most severe consequences including miscarriage 1, 2, 4
• Periconceptional period: When infection occurs within 2 months before or after conception, congenital infection rates are 3.8%, with a notably high miscarriage rate of 66% among infected fetuses 3
• Later pregnancy: Transmission rates increase dramatically to 44% at 26 weeks and 71% at 37 weeks, though disease severity decreases 2

Evidence for Miscarriage Association

Recent meta-analysis data strongly supports the association between toxoplasmosis and spontaneous abortion:

• Women with recent T. gondii infection have 3.72 times higher odds of spontaneous abortion (95% CI: 2.21-6.26) 5
• When specifically examining recent infections at the time of miscarriage, the odds ratio increases to 4.2 (95% CI: 2.04-8.85) 5
• Documented cases include two late miscarriages at 15 and 24 weeks among periconceptional infections 3

Clinical Presentation and Severity

The paradox of early infection is that while transmission is less likely, the consequences are most severe:

• Infection in early gestation typically results in more severe fetal involvement compared to later infection 1
• Most infected newborns (70-90%) are asymptomatic at birth, but the majority develop late sequelae including retinitis, visual impairment, and neurologic damage 1
• When symptomatic at birth, manifestations include chorioretinitis (92%), intracranial calcifications (80%), and hydrocephaly (68%) 2

Mechanisms of Transmission

Three pathways can lead to congenital infection and potential miscarriage:

• Primary infection during pregnancy (most common cause) 2
• Reactivation in immunocompromised mothers 1, 2
• Reinfection with a more virulent strain 1, 2

Important Clinical Caveats

The actual risk may be overestimated in clinical practice:

• A 2021 study found only 0.47% congenital infection rate overall in early pregnancy infections, with 0% in suspected acute infections and 2.8% in confirmed acute infections 4
• Many cases labeled as "acute infection" are based on low IgG avidity alone without true seroconversion documentation 4
• Early antibiotic treatment (within 3 weeks of seroconversion) can reduce transmission risk by 52% 2

Diagnostic Considerations

Proper diagnosis requires careful serologic interpretation:

• Single-point testing is often insufficient; serial testing is needed to confirm acute infection versus chronic infection 1
• IgM positivity alone does not confirm recent infection, as it can persist for months to years 1
• Low IgG avidity suggests recent infection but requires confirmation with repeat testing 4
• Fetal ultrasound should monitor for ventriculomegaly, hydrocephaly, intracranial calcifications, or growth restriction 2

Prevention and Management

For seronegative pregnant women, prevention is paramount:

• Avoid undercooked meat and unwashed vegetables 6
• Practice proper hand hygiene after handling raw meat or soil 6
• Avoid contact with cat litter or use gloves when necessary 6
• Quarterly serologic monitoring in initially seronegative pregnant women can detect seroconversion early 7