Like other preteens, Samantha Caraballo didn’t quite understand her period. She first menstruated when she was 11; then her period stopped. Feeling too awkward to talk about it with her mother or her doctor, she went without a period for two-and-a-half years. But when she turned 15 and suddenly gained 20 pounds, she realized she couldn’t keep her problem a secret anymore.

“I never wanted to talk to my mom about things,” Caraballo, 30, of Youngstown, Ohio, told TODAY. “But I thought, ‘what is going on with this body?’”

For the past six years Samantha Caraballo struggled with infertility related to PCOS. Courtesy Samantha Caraballo

A gynecologist diagnosed Caraballo with polycystic ovarian syndrome (PCOS), a disorder of the endocrine system that affects 8 to 10 percent of women of reproductive age and is a leading cause of infertility. Her doctor put her on birth control, which regulated her period and helped her drop the weight. That worked for a while, but she has since experienced random weight gain and hair growth. And, she's struggled to become pregnant over the past six years.

“I don’t think I have attended a baby shower in six years because I can’t,” Caraballo explained. “PCOS is frustrating as hell.”

Experts know very little about PCOS, one of the reasons that patients, like Caraballo, experience such frustration in trying to get help. A recent mouse study, which generated headlines that scientists had found a cause, sheds some new light on the difficult to treat hormonal disorder.

Researchers at Inserm in France noticed that pregnant women with PCOS had 30 percent higher levels of the anti-Müllerian hormone (AMH), a substance which surrounds the small egg follicles in the ovaries. The researchers wondered if excessive AMH in pregnancy contributed to PCOS in their female children.

So they exposed pregnant mice to AMH to create PCOS and found that their female offspring were more likely to have PCOS. What’s more, they produced extra testosterone. But if the mice took cetrorelix, an IVF medication, the condition diminished.

“This study is a radical new way of thinking about PCOS and opens up a whole range of opportunities,” Paolo Giacobini, an author of the study and a neuroscientist at Inserm, told TODAY, via email.

Researchers will need to conduct similar tests in human, but reproductive specialist cautions against too much excitement — any new treatment would be years away.

“They identified a potential cause for PCOS for some women,” said Dr. Maria Menke, a reproductive endocrinologist at Magee Womens Hospital of UPMC, who was not involved in the study. "This might help a certain subset of women, but it might not be the treatment for all of them.”

Why PCOS evades understanding

The causes of PCOS and why it varies among patients are not well understood, although it's likely that both environment and genetics play a role. Women with sisters or mothers with PCOS have a higher chance of having it, said Dr. Christine Greves, a doctor at the Center for Obstetrics and Gynecology at Orlando Health.

“The cause could be multifactorial,” Greves said.

To be diagnosed with PCOS women must meet two of three criteria, which include:

Excessive testosterone

Irregular ovulation

Polycystic ovaries

Symptoms can also vary widely. Some, like Caraballo, struggle for years with infertility, while others get pregnant immediately. Other women experience insulin resistance and metabolic disorder and struggle to lose weight. Others see no weight gain.

“When a patient walks in with PCOS the thing I ask is ‘What is their goal and main concern?’” Menke said. “Is it regulating your period? Getting rid of your hair?”

That determines treatment. Most doctors put women on birth control to regulate their periods. Regular menstruation is important because a build-up of the uterine lining can lead to endometrial hyperplasia, marked by heavy bleeding. Women with PCOS often think this is their "normal", but it can be a sign of endometrial cancer in rare cases.

“Women think ‘I just have heavy bleeding, no big deal,’” said Greves. “Heavy bleeding and periods that are not regular make me nervous.”

For those with insulin resistance, diabetes drugs may help regulate weight and blood glucose levels. Medications to encourage egg production to aid with fertility have varying success. While not much has changed in the treatment of PCOS for years, experts believe they understand how to use therapies more effectively.

“We’re better at identifying patients who need certain types of treatment,” Menke said. “It is a long journey if they have PCOS."

Samantha Caraballo's painful journey may have a happy ending, after all: She’s pregnant and due in November.

“It has been a long emotional road,” she said.