As a Cat parent, I know how troublesome it is if you have a new born kitties but it keeps pooping everywhere inside your house, so by sharing this few method, I hope your little kitties can learn how to properly use a litter box a.k.a their own toilet. Okay so the first thing you wanna do is by having a litter box, its basic and you have to do it, place your litter box in a quiet, clean and easy to reach, especially for your cat, and make sure the litter box is clean so that your cat can use it with ease. The next thing you wanna do if your cat / kitten didnt want to use the litter box is to train them thoroughly by introducing them slowly to the litter box, everytime you see them sniffing around, take them to the litter box and watch them, and make sure to take them to the litter box every morning to make them familiar with it. and, again, lastly, but not last, please make sure to clean the litter box every single day because your cat might not want to use it if it is dirty, and please be caution if you're pregnant, dont clean the litter box yourself make someone else do it for you. If you have already done all of that, but your cat still dont want to use the litter box, you might consider making the litter box more appealing, or move them to a quieter area, this might help you somehow, or if it still fails some feline will stop using litter box if they have urinary infection, so you might want to visit your veterinarian. Well, good luck.