Menounos said becoming a mom has been "better than I could’ve ever imagined."
Son Wren's birth comes just five months after the arrival of their daughter Esti in January.
Obregón, who met her granddaughter at a Miami hospital last month, said her son's "last wish" was "to bring a child into the world."
The "Charlie's Angels" actor welcomed her son via surrogate in 2015.
Some adoptive, surrogate and queer parents are able to nurse their babies by inducing lactation.
Experts share the best ways for parents to talk to their children about traditional and gestational surrogacy.
The photo was released the day of the premiere of the new season of "The Kardashians."
"Like a third of Americans trying to conceive, our path to parenthood was the complete opposite of a textbook experience."
"Is that a weird thought?" the Bravo bigwig asked Sirius XM host Jeff Lewis.
The "Elementary" star welcomed a son, Rockwell Lloyd Liu, in 2015.