"Generation Y" people in urban areas have been found to have had an average of five sexual partners and had their first sexual experience when they were 15, the Thai Health Report 2016 revealed Thursday.
The report, which was jointly compiled by Mahidol University's Institute for Population and Social Research, and the Thai Health Promotion Foundation (ThaiHealth), focused on differences between Gen-X (born 1961 to 1981), and Gen-Y, or the Millennials.
The report focused on Gen-Y people born between 1982 and 2005 who live in urban areas.
"Males and females aged between 15 and 19 tend to have a higher average number of sexual partners and engage in their first sexual experiences earlier than both genders in previous generations," said Mr Chalermpol Chamchan from the Institute for Population and Social Research at Mahidol University.
Major factors that drive the "Millennials" to enter into sexual relationships earlier include rapid changes in social context, customs and the environment, Mr Chalermpol said.
Widespread access to the social network where porn chat rooms, photos and videos are widely available also increased Gen-Y's sexual arousal, he added.
"We did not worry only about teenagers having sex early, but also them engaging in unsafe sex," Mr Chalermpol told a press conference held at ThaiHealth Thursday.
He pointed out that sex education is a significant tool for better and safer health for Gen-Y and another generations.
"Trying to stop the youngsters from having sex is impossible because the world is moving fast. You can't catch up with them," Mr Chalermpol said.
In Thailand, Gen-X is a dominant presence with 23 million people aged between 35 and 55 years old, making up 47% of the country's labour force, followed by 22 million in Gen-Y, he said.
He said that Gen-Y men get married when they are 29-30 years old, while Gen-Y women are usually ready to tie a knot when they turn 28. "Late marriage is becoming a very clear trend."
Millennials showed no desire for having kids due to their fear of losing freedom in their lives. He said 36% of Gen-Y women saw having kids as an obstacle to their freedom, while 20% said growing social problems could pose threats to their children's lives.