We'll,If you need to know you're sim's or sim is pregnant you gotta here the chimes when there done "Trying for baby" or just wait intill you're sims moodlet has a throw up looking face that is green then click "x" and then look for the green throw up looking face and move you're toggle there then look to the right and scroll to the bottom of that moodlet and look for a "(Unkown Causes)" or "(Unkown Cause).That would tell you that you're sim is pregnant those are the only to options to know,If you don't hear chimes try many times and if you still did not hear chimes when the sound is low or you have the sound off if you keep it this way just wait intill the green throw up looking moodlet shows up.
I know that's alot in those two options,This only works on Xbox 360 only.I don't know if it would work on other consoles.