Monica Cellio's answer already mentions recommendations if you own a cat and most of all that you're much more likely to contract toxoplasmosis through undercooked meat (most of the contamination cases) and gardening — you may add insufficiently washed legums and fruits. There are much more informations on the CDC website.
I feel it's also important to understand why the risks of being contaminated by a cat is small :
- the cat can contaminate only once in his live ;
- it takes 2 to 5 days for the eggs to develop under good conditions (that is, feces of an infected cat cannot contaminate you the first day, hence the recommandation to clean the litter everyday) ;
- eggs need good conditions to develop (e.g. feces in litter or soil) ;
- the cat will be able to contaminate for only a few days to a few weeks (possibly longer if he has specific diseases like FIV or FeLV) ;
- you'd have to ingest those eggs contained in (few days old) cat feces to be contaminated.
If you follow basic hygiene rules, it's unlikely that the conditions are met. It's even more unlikely if your cat never goes outdoor and only eats commercial cat food.
However there is no zero risk, and indeed consequences on the baby can be quite terrible, so it's important to be particularly careful during the pregnancy. But again, pay more attention to your food, because it's by food that you're most likely to contract toxoplasmosis.
(Disclaimer : I'm neither a physician nor a vet, just reporting informations published on other (trustable, IMO) websites.)