Molly Ringwald Says Daughter Was Conceived In Studio 54 Dressing Room

Molly Ringwald had a night to remember back in the day ... because she says her daughter was conceived at the famed Studio 54 -- albeit, well after its heyday.

The actress shared the intimate deets with The Times, saying her daughter Mathilda came to be through a sex session she had with her husband Panio Gianopoulos -- explaining they banged in a dressing at Studio 54 while it was being used for the Broadway show 'Cabaret.'

Molly says this happened toward the end of her run with the production in '03 -- and it sounds like part of the reason was because she was getting a little old to have children.

MR explains ... "I always knew I wanted to have children but it took me a while -- I was 36 when she was born. At that age the biological clock is a real thing and it had kind of become deafening. All I could think about was: must have kids."

On the topic of being a mom, Molly says this ... "The hardest thing about motherhood was realizing that my time was not my own. As an actress, I've traveled a lot and learned to live with instability, but that's not great for kids. That's something I am always looking to improve on and luckily I have a husband who is a planner and is very stable."

Molly's also the proud mom of fraternal twins Roman and Adele -- whom she also shares with Panio, who she married in 2007.

Molly and Mathilda are tied at the hip these days -- and she's following in her mom's footsteps too ... undertaking a career in Hollywood.