The couple will welcome the baby in February (17).

Mo's mother, Tabitha Brown Pitney, broke the news to friends and family in a post on Facebook.com, in which she shared photos of her son and daughter-in-law wearing denim overalls while holding up a matching baby-sized outfit and a sign which reads, "Boy or a Girl Thing?", a reference to his recent single, Boy and a Girl Thing.

The grandmother-to-be captioned the images, "Well it's official. I'm old".

Pitney and his wife wed in March (16).