What is going on with my Sim in Sims 3?

Okay, so I have a family of 5. The mom and dad tried for a baby, and I didn't hear the lullaby sound, but the next day, the mom felt nauseous. Then, she changed into maternity clothes. But, she hasn't had back pain yet, and it's been 2 days. Also, you are only supposed to have 4 days off on maternity leave, but it says she doesn't go back to work for 10 days! Please help! I don't know what to do! By the way, she's already had 3 children, and there were no problems during the pregnancies. This is her 4th child. I'm afraid she isn't going to have the child! :(