"I got some bad news today and didn’t have anyone to share it with... but I guess I gotta tell someone," she said alongside a photo of herself looking pensive.
"To all the women out there struggling with fertility, I feel ya. The universe works in mysterious ways and sometimes it all doesn’t make sense... but I hope there’s light about to shine through all the dark clouds."
Actress Jillian Bell commented, "Sending you love Rebel," while her Pitch Perfect co-star Alexis Knapp added, "So sorry my love. Been through it."
Many others shared their support for the star with one follower writing, "Here in solidarity with you! I’m an OBGYN and only 36 [years old] and I spent my life on my career, trying to freeze my eggs from ovaries that no longer care. It’s like I traded smarts and professional gains for my fertility only no one told me."
The actress has been open about her fertility struggles in the past and revealed last year she had made the decision to freeze her eggs.
During an Instagram Live, she told her followers, "As all good career women out there should know, if that’s something that interests you, it’s a pretty good time to do it. Getting to your 40s is kind of even leaving it a little too late. It’s better to do it a bit earlier if you can."
It comes after Rebel's 'year of health' which saw her lose about 30kg over 12 months.
Speaking with E!, the star revealed last year she struggles with polycystic ovarian syndrome.
"I’ve been overweight for about 20 years. I started gaining weight when I was about 20," she said. "I had something called PCOS – polycystic ovarian syndrome – and I gained weight rapidly.
"It’s just a hormone imbalance and you gain a lot of weight usually and that’s how it manifested in me. Sometimes I feel sad, but then at the same time, I worked my body to my advantage. I like being all sizes. It’s just now turning 40, I am more health-conscious and thinking of starting a family."
Speaking of her weight loss journey, Rebel said: "Drew, for the last few years I've been theming my years, so I had the Year Of Fun, last year I had the Year Of Love and this year I’m like, 'It’s going to be the Year Of Health,' because I turned 40 this year in March and I never really focused on my health which was probably obvious."
She shared how becoming famous internationally was so stressful and her health took a backseat.
"I was going all around the world, jet setting everywhere and eating a ton of sugar that was kind of my vice,” she said.
"I have a very sweet tooth, I love desserts. I’ve tried, like so many women out there, fads and diets and things before and I’m like I need to do a really holistic approach this time."
She then focused on the emotional aspects of her eating habits. "I think what I mainly suffered from was emotional eating and dealing with the stress of becoming famous internationally,” Rebel said.
"There is a lot of stress that comes with it and I guess my way of dealing with it was just like eating donuts."
"So I was working on the mental side of things of why was I doing that and why was I not valuing myself and having better self-worth. And then, also on the nutritional side my diet was mainly all carbs, which are delicious, but for my body type I needed to eat more protein," she explained.
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