Ashlee Simpson posts bubble bath throwback as she wishes big sister Jessica a happy 40th birthday

Ashlee Simpson wished her big sister and ‘best friend’ Jessica Simpson a happy 40th birthday on Friday. 

The singer, 35, sent her well wishes on Instagram, where she posted a throwback of the future superstars taking a bubble bath as young girls.  

‘Happy Birthday big sis!! You are forever my best friend and inspiration and I’m so lucky to call you my sister. I LOVE YOU,’ she captioned the snap, along with an emoji of two dancing women.

In the adorable photo, the girls were covered in bubbles as they soaked inside their tub.

One of the girls flashed a huge smile for the camera, while the other flashed a slightly annoyed expression.

Jessica officially turns 40 years old on Friday, but the singer was already celebrating on Thursday when she posted a snap of herself wearing her 14-year-old True Religion jeans. 

The mother-of-three looked strikingly slim in a mirror selfie where she posed in tight distressed denim which showcased her 100lb. weight loss.

The former pop star took the snap in her bedroom at the home she shares with husband Eric Johnson and their kids Maxwell, eight, Ace, seven, and Birdie, 15 months.

Her legs looked ultra-svelte in the frayed blue jeans, which she paired with a trendy tie-dye hoodie.

In the caption alongside the picture, Jessica wrote: ‘I have kept these throwback True Religion jeans in my closet for 14 yrs (I’m not exaggerating!).

She added: ‘I figured that since I’m in the final hours of my 30’s I’d give them another try, and hello 40, so nice to meet you.’

Last September Jessica opened up about her 100lbs weight loss achievement on Instagram.

Along with a chic outfit selfie, she wrote: ‘6 months. 100 pounds down (Yes, I tipped the scales at 240.’

‘My first trip away from #BIRDIEMAE and emotional for many reasons, but so proud to feel like myself again. Even when it felt impossible, I chose to work harder.’