Abstract Objectives: Toxoplasma gondii and parvovirus B19 (PVB19) infections in a healthy adult are usually asymptomatic. Congenital toxoplasmosis is the cause of hydrocephalus, chorioretinitis and intracranial calcifications. Hydrops remains the most common complication during the fetal PVB infection. The aim of the study was to analyze the complications during pregnancy in women with serological features of acute toxoplasmosis or acute parvovirosis. Material and methods: In our study, we have included 1800 pregnant women, hospitalized in Department of Fetal-Maternal Medicine and Gynecology Research Institute, Polish Mother's Memorial Hospital (RIPMMH) in Lodz, (Poland) between 2000-2007. Anti-T.gondii antibodies were tested by ELISA Vidas Toxo IgG, ELISA Vidas IgM (BioMerieux) and Platelia Toxo-A Anti-PVB19 antibodies were detected by NovaLisa Parvovirus B19 Recombinant IgG-ELISA and IgM-ELISA (NOVATEC). Results: Prevalence of IgG anti-PVB19 among pregnant women was 35% (n=633). IgG anti-T.gondii was noticed in 55.5% (n=910) of women. Serological features of acute parvovirosis were demonstrated in 13.5% (n=243) of the patients and 14.2% (n=256) of women suffered from acute toxoplasmosis. Fetal hydrocephalus or ventriculomegaly was diagnosed in 19.5% (n=64) of the pregnancies with IgM anti-PVB19 and in 7.3% (n=19) women with serological features of acute toxoplasmosis. In 8.5% (n=28) of the patients with IgM anti-PVB19 and 9% (n=5) of the pregnant women with IgM and/or IgA anti-T.gondii, fetal hydrops was detected. Intrauterine death was diagnosed in 4.5% (n=15) of the cases with acute PVB19 infection and in 2.3% (n=6) of the patients with acute toxoplasmosis. Amniotic fluid disorders were noticed more often in women with acute parvovirosis (polihydramnion 15.5%, n=51; oligohydramnion 8.5%, n=28; ahydramnion 6.3%, n=21) than in those with active toxoplasmosis (polihydramnion 3.4%, n=9; oligohydramnion 3.4%, n=9; ahydramnion 0%). We have examined also the influence of T.gondii and PVB19 infections on an intrauterine growth restriction, preterm delivery and spontaneous abortions. Conclusions: In conclusion, infections of T.gondii and PVB19 are a very common cause of complications in pregnancy. Due to high prevalence rate of IgG antibodies in Poland, it is necessary to consider routine serological testing in pregnancy.