Last night, I made my start on Generation 3, with my heir, Alf Baulaire, and his childhood friend, high school sweetheart, now husband, Alexander Goth. They literally managed a Try For Baby in the rooftop hot tub before I had to send Alf off on his first day of work as a Secret Agent, so Alexander was home alone.
Back downstairs, I was cycling through topping off his motives preliminary to sitting him down to hammer out a Freelancer Writing gig, and so though he wasn't in the amber zone yet, I had him visit the toilet to top off his Bladder meter. Clicking on it, I was immediately offered the options "Use" and "Upgrade" (greyed out - he doesn't yet have the skill), but also "Take Pregnancy Test" and "Throw Up".
The latter looked pretty persuasive of pregnancy for me - I don't let my Sims near spoiled food, so I never see "Throw Up" otherwise, but I spent the 15 and had Alexander use a pregnancy test. I like to know right away! But even so, there are usually indications.