In the 5th season, Olivia asked Elliot about Kathy's pregnancy-related to Fetal Alcohol Syndrome- if she got pregnant again, would Elliot let her drink alcohol? Elliot jokingly remarked that if Kathy got pregnant again, he would shoot himself. He then continued on that now knowing about Fetal Alchol Syndrome, he trusted Kathy to make her own decisions as she's given him four healthy children after having a glass of wine every now or then. At the time, Elliot truly believed that he was done with having kids. But 3 years/seasons later, Kathy was pregnant again.
The next day, Elliot was still in shock. Olivia realized it and asked what was wrong? Elliot told her that Kathy was pregnant and went down on himself for being pathetic, fumbling around like a kid. Olivia asked what he was going to do but Elliot didn't know what she meant by that. They were interrupted before Olivia could explain. Elliot moved back home (offscreen)
Other than that, Kathy had her cravings of peanut better and tacos while being over 40. At one point, Elliot was concerned over the baby's health with all the risks that could happen but felt it was better not to know from the Doctor as they're Catholics.