R&B star John Legend and his wife Chrissy Teigen are expecting their second child.

The model, who has been open about her struggle with fertility issues, broke the baby news to fans on Tuesday (21Nov17) via a sweet video post on Instagram, featuring the couple's one-year-old daughter Luna.

"Luna, what's in here?" the mother-to-be can be heard asking, referring to her stomach, prompting little Luna to reply, "Baby!".

"It's John's!" Chrissy captioned the clip.

The happy news emerges weeks after the beauty told InStyle magazine's November (17) issue that she and John were planning to spend the holidays trying for another baby.

The 31-year-old revealed she was going to be implanted with a frozen embryo as part of their in vitro fertilization treatment to expand their family. The last time she did this, the couple ended up with Luna, and Chrissy hoped the third time would be a charm too.

"The first little girl didn't work, and then the second is Luna," she explained.

The pregnancy will give Chrissy and John something to be extra thankful for this Thanksgiving, which falls on Thursday (23Nov17), as it was the third and final embryo from a batch of 20 eggs they had previously had frozen.

Chrissy will also be keen to avoid another struggle with postpartum depression, a condition she suffered through following Luna's birth in April, 2016.

"I have really good days and really bad days, and I don't tend to talk about the really bad days," she told InStyle. "But I would hate for people to think those days didn't exist."