BOSTON -- There's a startling finding from one of the nation's top experts on sexual health.

It's common for women to temporarily lose their sex drive after giving birth. But some experts now say that as many as one in five of these women may never regain their sex drive -- at least not without treatment.

Seven years ago, Donna Doyle got something she always wanted -- a little baby boy. But what she didn't count on was what she would lose energy, her love of life and all that it had to offer.

"Your sexual interest in your partner, that's a part of your life and your relationship that I wasn't willing to walk away from," Doyle said.

Doctors first told Doyle what she was feeling was normal. They then suggested she had postpartum depression. But the symptoms went on and included other things, like muscle weakness. Even her hair became dry and brittle. For three years, she looked for an answer.

"That physical closeness is a lot of what your mental closeness is, and if that falls by the wayside, or frays, you lose I think an intimacy, a sense of teamwork a sense of being in life together," Doyle said.

After insisting on having some blood work, Doyle found the answer. The level of one of her hormones, testosterone, was unusually low.

That brought her to sexual health expert Dr. Irwin Goldstein and to a startling diagnosis. He believes one in five women who have had children, like Doyle, actually have a switch shut off in the body. They are no longer able to produce certain sex hormones.

"The hormones that are missing are what are called androgens," Goldstein said. "Without androgens, there is really no sexual function unfortunately."

Goldstein believes the change is permanent.

"The women go back to being prepubertal. They're like 5 years old in their sex steroid hormone levels in their bloodstream. Now, why it is they go back to prepubertal, we don't totally understand. But when you look at the blood levels of hormone in their bodies and compare them to their children, they are at the same level," Goldstein said.

The good news is there is a way to treat it, and it works about 70 percent of the time, Goldstein said. But the treatment may not be too appealing.

"To re-establish their function, as we did in Donna, we essentially put her back through puberty," Goldstein said.

That involves an array of hormones, gels, medications and devices tailored to each patient. It involves some side effects -- acne in some women, facial hair growth in others.

Doyle, who now also has a daughter, takes a daily DHEA hormone supplement and uses testosterone gel. She said that the side effects are minimal and well worth the benefits.

"It was dramatic," Doyle said. "It was me going from someone who battling energy levels, motivation, to I'm getting my sparky little person back who was me."

But Dr. Phillip McCrary urges caution. He said that in the vast majority of women, libido eventually returns on its own, and when it doesn't, it's more likely to be thyroid or relationship-related rather than hormonal.

"I wouldn't want this to emerge as being the reason for a lack of libido and have doctors reach for that magic pill and ignore the social circumstances of the patient. I think that would really be a wrong thing to do," McCrary said.

For Doyle, the treatment has been successful. She's now enjoying her family, and is embracing a newfound desire to live life to its fullest.

It's important to note that Goldstein has not yet published this recent data but does have plans to do so. He has also found that low androgen levels following pregnancy tends to run in families and suggests that if you have had the problem, your sisters and daughters may also want to be tested after having children.