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Toxoplasmosis in Pregnancy

Author: Michael L. Socol, MD

Editor: Daniel JS Martingano, DO, MBA, PhD

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Toxoplasma gondii is a protozoan which can lead to human infection termed Toxoplasmosis. Transmission occurs via fecal-oral exposure of uncooked meat, contaminated soil or water, contaminated fruits or vegetables, or exposure to infected cat feces. Most infections are asymptomatic and nonspecific in immunocompetent individuals, with bilateral, symmetrical, nontender cervical lymphadenopathy being the most common physical exam manifestation, if present. Immunocompromised hosts (e.g. HIV infected individuals) can manifest such problems as central nervous system infection, myocarditis, or pneumonitis.

The reason this infection needs to be taken seriously is that if the infection is acquired by the mother in pregnancy, the parasite can result in significant adverse outcomes to the fetus. Congenital toxoplasmosis can cause debilitating neurological or ocular disease even resulting in blindness, while toxoplasmosis in pregnancy additionally carries an increased risk of miscarriage, preterm birth, low birth weight, and perinatal death.

The diagnosis is made by serology showing seroconversion from negative to positive IgM or IgG antibodies. Maternal IgG avidity testing may also be useful to assist with timing the primary infection for patient counseling. Universal screening is not recommended in countries with low prevalence rates such as the United States and Canada. Careful hand washing, washing of fruits and vegetables, and avoidance of cat litter or uncooked meat are all advised.

Congenital infection increases with gestational age and is most likely to occur following maternal infection in the third trimester, although first trimester fetal infection is more likely to lead to clinical sequelae.  Most infected fetuses are asymptomatic at birth.  Characteristic ultrasound findings include hyperechoic intracranial calcifications, ascites, and cerebral ventriculomegaly/hydrocephalus, which carry a poor prognosis.  The diagnosis of congenital infection can be confirmed by PCR of amniotic fluid obtained through amniocentesis. 

Toxoplasmosis in pregnancy should be managed by a Multi-disciplinary team including maternal-fetal medicine, infectious disease, and neonatology specialists to review available data and help the patient make an informed decision. Treatment regimens often include pyrimethamine, sulfadiazine and folinic acid. Spiramycin is also included to reduce transplacental transfer of the parasite, although spiramycin is still considered experimental in the United States and is not readily available

Further Reading:

Ahmed M, Sood A, Gupta J. Toxoplasmosis in pregnancy. European Journal of Obstetrics & Gynecology and Reproductive Biology. 2020 Dec 1;255:44-50.

Duff P, Creasy RK, Resnik R, et al., Maternal-Fetal Medicine: Principles and Practice. Maternal and fetal infections.  8th Edition, Saunders, 2018.

American College of Obstetricians and Gynecologists, Practice bulletin no. 151: Cytomegalovirus, parvovirus B19, varicella zoster, and toxoplasmosis in pregnancy. Obstet Gynecol. 2015 Jun;125(6):1510-25. doi: 10.1097/01.AOG.0000466430.19823.53.

Initial approval October 2008. Revised January 2015. Revised July 2016. Reaffirmed January 2018. Revised July 2019; Reaffirmed May 2021; Revised November 2022


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This document is designed to aid practitioners in providing appropriate obstetric and gynecologic care. Recommendations are derived from major society guidelines and high-quality evidence when available, supplemented by the opinion of the author and editorial board when necessary. It should not be construed as dictating an exclusive course of treatment or procedure to be followed.

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