To become infected with toxoplasmosis, there are several conditions that must be met. Of course, no one wants to become infected, but I present it this way to demonstrate how much effort is needed to do it.
First, you must own or obtain a cat that is infected with the organism, Toxoplasma gondii. It's not a bacterium, it's not a fungus, and it's not a virus. It's what is known as a protozoan, a tiny, one-celled parasite... kind of like an amoeba, but crescent-shaped, if you have a microscope and want to look at one.
To find out if your cat has it, have a veterinarian test for it. However, this involves doing a blood test called an "antibody titer," but it's not diagnostic unless a series of tests can be performed over time. If the titer is positive, it means the cat is pretty much immune, as antibodies are present to fight off current and future infections. This is true of humans as well. Therefore, a pre-pregnancy antibody test that yields a positive result means mom is immune, too.
However, if you're not immune, the next thing to do to become infected is to make contact with the parasite's eggs. But not just a touch... you have to eat them. Ugh. How does that happen? During the only two weeks in the cat's life when the parasite is shedding its eggs into the host cat's feces, a human must touch them, then somehow get the infectious material into their own mouth. But not right away. If you do it too soon, the eggs won't mature and you won't be infected. You must wait 1 - 4 days, when the feces are dried enough for the eggs to be "potent." Scientifically, it's called "sporulated."
Consequently, if you are cleaning the litter box every day, this can't even happen.
But there's more. Other conditions must be met at the same time.
"Ideally," this must be your first cat, preferably a kitten, since they haven't had a chance to develop immunity from several exposures yet. If you've ever owned cats before, or have one now that's been in the family a long time, the chances of infection are actually negligible. Why?
Because you will be immune by now... and so will the cat. Since exposure is rather common, both you and your cat will have had time to develop some immunity to it.
Also, this infection is a one-time thing, so no treatment has been invented, except for humans. Once the parasite has run through its life cycle, it's over. The cat must become infected again to be infectious again. But the cat's own immune system will be stronger, and spreading the condition to others is even less likely. In fact, repeated infection, as by cats who hunt and eat infected mice (the most prevalent host), leads to a form of "natural vaccination," eventually rendering the cat non-infectious. However, this doesn't mean it's OK to let the cat keep getting infected. They could actually become sick from the disease state of Toxoplasmosis and die.
Now, if you really want to scare yourself and take a chance that the infection will harm your fetus, you must become infected during your second or third trimester of pregnancy. This is the time when you might have some transplacental transmission of the parasite into the baby's bloodstream, and on to the small intestine, where the "oocysts" (the parasite's eggs) can hatch and grow. However, even with such infection, the odds are still greatest that the baby will be born normally and totally healthy.
Just when you thought you were through, there is yet another condition to be met. It's called immunity. Just in case you have a very poor immune system, the chance of infection, though small, is still there.
However, while the incidence of toxoplasmosis is extremely low among healthy humans, it actually is quite high among AIDS victims, who have little or no immune strength left at all. Those who have pet cats and come into close contact with them are more than likely to become infected. But pregnancy has nothing to do with it. Companionship is more important at such times, and so it's best to leave these happy relationships alone, offering support by relieving them of those cleanup chores that present the most risk.
But there is yet ONE MORE condition to consider, and it has nothing whatsoever to do with a cat! Just eating undercooked meat can do it, too.
The main thing you don't have to do is get rid of your cat.
Sources: The Cornell Book of Cats, Cornell University; The Merck Veterinary Manual, Merck & Co.
Feel free to download a brochure on this subject at my website: The Problem Cat
Look through the center column of Free Reports. In fact, download anything there that looks interesting to you.