Girls usually don't have to worry about going through puberty until they are at least 10 to 13 years old — but, for one English girl, the process started much earlier, according to a report in the Daily Mail.

While her toddler friends enjoyed life's simplest pleasures, Hayley Smith spent her time dealing with menstrual pains.

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She also had put up with other realities of puberty including body odor, greasy hair and mood swings.

Her parents, Debbie, 41, and David, 45, were both left baffled by the changes in their daughter's body, and behavior.

"I first noticed Hayley had body odor shortly after she'd turned three," said Debbie, who also has a 12-year-old son, Carl.

"Around the same time, she suddenly gained a lot of weight, despite not eating any more than she usually did. I thought it was very odd, and I mentioned it to my mother."

A series of tests with an endocrinologist revealed that Hayley's bone age was advanced, but no firm diagnosis was reached.

"The endocrinologist may have dismissed my worries, but I could just tell that my daughter was entering puberty."

Her instincts proved to be correct. After several examinations and tests over the following 18 months, Hayley was finally diagnosed with precocious puberty at the age of six. The condition, in which puberty begins at an unusually early age often due to abnormal production of estrogen, is thought to affect as many as one in six children under ten.