Singer/actress Jamie Lynn Spears has become a mum of two after giving birth to another baby girl.

Britney Spears' younger sister and her husband Jamie Watson welcomed Ivey Joan Watson on Wednesday (11Apr18) in Covington, Louisiana.

"We are beyond excited to welcome this beautiful baby girl to our family!" Spears tells People magazine. "Her middle name, Joan, is to honour my Aunt Sandra, who passed away 10 years ago from ovarian cancer. She was the most graceful woman I've ever known."

Jamie announced her pregnancy in December, revealing her her nine-year-old daughter Maddie, from her previous relationship with her ex-boyfriend Casey Aldridge, was going to be a big sister.

"Looks like we are starting off 2018 with another big milestone... sooo (sic) happy to announce that Maddie is FINALLY going to be a big sister," she wrote beside a family photo, posted on Instagram.

In her pregnancy announcement in December, the 27-year-old also reflected on the past year, during which she almost lost Maddie after she was involved in a scary all-terrain vehicle (ATV) accident in February, 2017.

"2017 was filled with some of the biggest challenges of my life, as well as some of the biggest blessings, so I made a choice to lay low this year to focus on truly becoming my best self as a person and as an artist," she continued.

"During that time, I continued working on my music and telling my story, which has created some of my most honest work and I (CAN'T) wait to share that with you all very soon. 2018 is going to be filled with many milestones both personally and professionally..."