The quirky New Girl actress, 34, and the producer, 42, are eagerly anticipating the arrival of their little one this summer.
Us confirmed that the two were dating last August, after Deschanel split from her boyfriend of two years, screenwriter Jamie Linden. Later that month, Deschanel and Pechenik made their red carpet debut together at the 2014 Emmys at the Nokia Theatre in L.A. (Deschanel was previously married to Death Cab for Cutie lead vocalist Ben Gibbard, whom she divorced in 2012.)
Deschanel's pregnancy overlaps with that of her famous big sister Emily Deschanel, who is currently expecting her second baby with David Hornsby. Luckily, Zooey will receive great advice from her sibling, who told Us Weekly she was handling her pregnancy like a health nut.
"I work with a nutritionist to make sure I have the protein that I need," Emily told Us last month at a Bones party, adding that her pregnancy craving was lemonade.
"It's so weird," she added. "I just get thirsty. You have to drink more water and I can only drink so much water. I used to drink a ton of [fluids] and now I've hit my limit so I think of a variety. Once I get thirsty, I'll want lemonade or a sparkling water. Maybe it is citrus fruits!"
Both sisters' tots will join Emily's 3-year-old son Henry, who was born in September 2011.
Sign up now for the Us Weekly newsletter to get breaking celebrity news, hot pics and more delivered straight to your inbox!