Researchers have learned much concerning the population biology of Toxoplasma gondii over the past 2 decades. It is now apparent that many atypical genotypes exist besides the typical 3 genotypes (type I, type II and type III) first described from samples from Europe and the United States. These genotypes can differ in pathogenicity and transmissibility from the typical genotypes that have been used in the majority of scientific research over the past 70 years. These differences impact much of what we used to believe as facts about congenital toxoplasmosis (CT) and will be important in developing new recommendations for prevention of CT and the monitoring of women at risk for developing CT. The present review highlights new information on T. gondii genotypes and how this information will change the way we convey information about CT to pregnant women, physicians and students.