Carrie Underwood doesn't know if she'll ever ''figure out'' raising two children.

The 36-year-old singer and her husband Mike Fisher welcomed son Jacob - a sibling for four-year-old Isaiah - into the world in January and she admitted they are still adjusting to life as a family of four.

She said: ''We're still figuring out our groove, to be honest.

''I don't know if we'll ever figure it out.''

The 'Love Wins' singer is delighted Isaiah has taken to life as a big brother really well, admitting there is already a ''really cute'' bond between her sons.

She said: ''He loves it. He calls Jacob 'My baby.' [He says] 'Where's my baby? How's my baby? I wanna kiss my baby.' ''

Last month, Carrie admitted she'd found it hard for her body to ''bounce back'' after giving birth to Jacob and she thinks it's important to show that even famous people struggle with the same challenges others do.

She told E! News: ''People expect more of us 'celebrities'. Everyone is busy showing the highlight reels of their life, but life is messy.

''I'm a mom first and foremost. That's my favourite. I love my job but that's my favourite role to play.''

After admitting she had been ''pretty hard'' on herself for not being able to work out the way she used to, the 'Cry Pretty' hitmaker recently vowed to ''start appreciating'' her body and ''stop analysing every angle and every curve''.

She wrote on Instagram: ''As I prepare for red carpets and for life on tour, right now I make a promise to myself to start appreciating what my body CAN do and stop focusing on what it can't. I promise to stop analyzing every angle and every curve and every pound and every meal.

'''m going to keep staying the path because it is a journey and as long as I'm always working towards my goals, one day I'll reach them. I'm going to take it day by day, smile at the girl in the mirror, and work out because I love this body and all it has done and will continue to do! #bodyafterbaby #fitmom #healthy #staythepath @caliabycarrie. (sic)''