The cure for ants in your yard is beneficial nematodes. They are microorganisms that you spray on the yard and they eat the ant eggs from the nest in the ground. I've been using them for 5 years now, and haven't had an ant bed in the yard since I started using them. You can get the beneficial nematodes at any plant nursery that sells organic products - at least you can get them in Texas. It's too late to put them down now, you do it in the spring and they work all summer and fall and they keep the ants (especially fire ants) away. I'm not sure if they are widely available in other states??? If the winters are real cold, they will die - and you will have to put them down every spring. But in central and south Texas they will survive the winters and I only have to put them on the yard every 3 years or so. They eat flea eggs too, so you won't have any fleas in your yard either!
Of course, that doesn't mean that your baby won't get fleas from walks or other pets.