Unused cat litter does not have any effect on pregnancy, but a certain parasite found in feline feces in soiled cat litter presents a danger to pregnant women, notes WebMD. This parasite causes toxoplasmosis, a common infection found in people, birds and animals. This infection can cause brain damage or vision loss in a developing baby still in the womb.
WebMD advises pregnant women to avoid any areas or objects that might be infected with the parasite. Pregnant women are warned against changing a cat's litter box or digging in soil since it might contain infected cat feces. Additionally, pregnant women should avoid any area where a cat might have walked or defecated and should not eat food that has touched surfaces where a cat might have walked.
According to WebMD, chances are low that a pregnant woman will get infected and then pass toxoplasmosis on to her child. Also, if a woman has already had toxoplasmosis, she is probably immune to the infection. If she is immune, she cannot get the infection again and cannot pass the infection on to her child. A blood test can confirm the presence of toxoplasmosis, and an antibiotic is prescribed to treat the infection.