Brooke Shields is sharing a personal story about the "excruciatingly painful" miscarriage she had when she was younger, calling it the "worst twelve straight hours of [her] life."

The Blue Lagoon star opened up about the traumatic experience in her new memoir Brooke Shields Is Not Allowed to Get Old, explaining how an irregular pap smear in her mid-30s led to her having a cone biopsy to remove abnormal tissue from her cervix, per People. The procedure that caused scar tissue that doctors told her could make it difficult for her to conceive, so when she got married, she went back to a doctor to "get checked out."

Shields ended up doing in vitro fertilization (IVF) to get pregnant, and while her first round was initially successful, the tides changed a few months later and culminated in a "violent" and "painful" miscarriage.

"Amazingly, that first IVF round was successful, and I became pregnant — only to miscarry three months later. And what ensued was probably the worst twelve straight hours of my life," she wrote. "This miscarriage was so violent and excruciatingly painful that when it came time for a second IVF attempt I actually asked my doctor, 'Do you think it hurt so much because the scar tissue was getting stretched? Is that possible??'"

A female fertility specialist told her the biopsy is likely what made it difficult for Shields to get pregnant, something she wish she had been told by her first male doctor before undergoing the procedure.

"Had I been aware of the risks, I could have made other choices to support my fertility," she said.

The Endless Love actress went on to welcome two daughters, Rowan, born in 2003, and Grier, born in 2006.

Shields also recently shared a hilarious memory about making late Friends star Matthew Perry laugh on set while filming a scene together on the beloved sitcom.

Brooke Shields Is Not Allowed to Get Old is available now.

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