'Sexting' is becoming the new first step to sexual activity for adolescents, a new study has suggested.

Research conducted in Texas found sexting, defined as sending sexually explicit pictures or asking to receive one, is becoming a part of growing up for some teenagers before they become sexually active.

A group of almost 1,000 adolescents in Southeast Texas answered anonymous surveys detailing their history of sexting, sexual activity and other behaviours in an original six-year study.

The original study found that one in four teenagers had sexted, and that sexting was related to sexual behaviour.

Jeff Temple, an associate professor and psychologist at the University of Texas Medical Branch at Galveston, and his colleague Hye Jeong Choi, then examined the data from the second and third year of surveys to establish if sexting led to risky sexual behaviours, or if risky behaviours came first.

They concluded those teens who sext do not necessarily engage in risky sexual behaviour later on. Their results were published in the journal Pediatrics.

“Sexting preceded sexual behaviour in many cases,” Mr Temple told the Washington Post. “The theory behind that is sexting may act as a gateway or prelude to sexual behaviours or increases the acceptance of going to the next level.

“This behaviour isn’t always new, it’s just a new medium,” he added. However, he cautioned: “It’s not safe because it can be shared.”

He welcomed the findings as a “call to arms to talk to your kid about sexual health or behaviour."

“I think the really cool thing about this study in answering the question of what comes first is this could hold the key to prevention programs,” he said.