Kim Kardashian shared with fans a cute photo of Saint West riding a tricycle.
The snapshot shows Saint dressed in a Harley Davidson baseball tee and sweatpants as he plays on a Big Wheel.
The pair appeared to be at a farm or petting zoo, as bales of hay can be seen in the background.
Kardashian and West, who married in May 2014, are also parents to 4-year-old daughter North West.
Kardashian said in a video on her website in October that North is "still jealous" of her little brother.
"Obviously North loves Saint, she just is still jealous," the mom-of-two explained.
"She needs to still get it together and warm up and be a little bit nicer, but I think she's getting there," she said.
"I saw glimmers of hope a week ago. She's not harmful, she's not hurting him or anything. She just doesn't want boys in her room."
Kardashian confirmed in September that she and West are expecting another child via surrogate.