In the season 3 episode Nanny From Hell, Jeff tells Larry that Susie is pregnant, so Larry tries to persuade the Greenes to hire a nanny that he knows. The pregnancy never gets mentioned after that episode, as far as I can tell. Did I miss something?
Susie Greene's pregnancy is referred to, obliquely, in just one subsequent episode. The actress, Susie Essman, described the situation in an interview for Something Jewish:
In series two, we're told Susie is pregnant but we never see a baby – what happened?
It was never mentioned again. There are so many inconsistences in the show. The only reason he had me pregnant was because of the episode where I fall out of a window on to a pile of sponge cakes. Then it was never mentioned again. The next season we make one little reference to it, in the episode with the studded sweatshirts, I made a reference to the fact that I loved designing clothes out of my own home because it was easy with the new baby. But it has never been discussed since.
The studded shirts episode was "Ben's Birthday Party" from season 4 (since the pregnancy was mentioned in season 3, not season 2 as the interviewer thought). Her line was
The thing that's so great about these shirts is that I've got the business from the house and I can take care of the baby.