Having a dog in the house has an effect on pregnant women. The reason is that dogs have a parasite: Toxoplasma gondii. Toxoplasma gondii is a small, invisible protozoan parasite. Healthy people infected with Toxoplasma gondii usually do not show obvious clinical symptoms, but for pregnant women, Toxoplasma gondii can be transmitted to the fetus through the placenta, causing a series of adverse symptoms such as microcephaly, small eyes, hydrocephalus, abnormal neuropsychiatric development, paralysis, convulsions, high fever, cyanosis, vomiting, rash, jaundice, and liver enlargement after birth. There are also individual differences in symptoms, both mild and severe. Having a dog during pregnancy has more or less adverse consequences for the fetus. It is important to stay away from all kinds of pets during pregnancy, not to keep dogs in the house if possible, and for other animals to avoid adverse conditions.