Serena Williams Gets Tummy-Tightening Procedure For Pre-Kids Confidence

Serena Williams took a moment for some self-care ... letting her fans in on a procedure targeting her birthing scars -- something that's been a hang-up for her since having kids.

The retired tennis legend shared an IG clip of herself getting a radio frequency skin-tightening treatment -- and as you can see ... she's lying on an exam table as a technician rubs an ultrasound-like wand over her stomach.

Serena explained the video was filmed during a Parisian getaway, where her thoughtful pal -- knowing full well she felt self-conscious about her tummy post-childbirth -- treated her to a day at Maison Lutétia spa.

Serena shared the clip 'cause she was blown away by the results of the treatment, which uses electromagnetic waves to tighten the skin by boosting collagen and elastin production.

Serena acknowledged her body may never fully revert back to pre-baby form, but she's delighted by getting a bit of a former figure back, which she says helps boost her confidence.

And of course ... she's happy for the scars, because they resulted in her two kids.

She adds, "I will always love my birthing scars but I just wanted to say thanks to my friend Mia and Nat for letting me know it’s ok to take time for myself away from work and kids."