Arya Cabutihan has only recently started to feel comfortable talking about sex.
"It's pretty fun to talk about such taboo topics with your friends, I think it's a little gossipy," she told the ABC.
"At the same time, it helps you grow closer to one another."
But the 18-year-old said her experience was far from the norm in the Philippines which "is still very much conservative" and sex education is "practically invisible".
"The general culture, when it comes to sex, is that we still refuse to talk about it in the open," she said.
In the Philippines, one in five girls becomes a mother by age 19, according to national health data.
Last year, the government declared teenage pregnancies a "national emergency".
But with a large generation gap between the Filipino youth and elders, Ms Cabutihan said young people were taking matters into their own hands.
"They struggle to connect with us because they don't understand how we grew up and they don't understand the way we think," she said.
Ms Cabutihan is among a group of teenagers who started Amarela, an initiative that makes sexual rights and reproductive health information accessible to young people from various backgrounds and gender identities.
They share information in a way that appeals to young people across social media channels — in English and Filipino — and organise talks and webinars.
They also work with well-established reproductive health organisations in the country to help them better connect with young people.
"We're trying to bridge that gap," Ms Cabutihan said.
The biggest youth population in history
When the UN this week pinned the world's population at 8 billion people, it brought youth issues into the spotlight.
Right now, there are more children alive on Earth than there has ever been.
And with fertility rates plummeting across the globe, there will never again be more children than there are today.
In regions such as South-East Asia — where more than half the population is under 30 — the youth cohort will play a crucial role in shaping their countries' economic development and success.
Elise Stephenson, an equality researcher at ANU, said although young people were a core, valued part of society, they often fell through the cracks.
"They are experiencing a lot of inequalities — varying levels of development, poverty and inequalities of other kinds," Dr Stephenson told the ABC.
"Being able to identify the fact that young people are critical and involving them right now in government processes and other processes is really integral to the success of future nations."
But where the systems aren't keeping up, there is a large cohort of young people who are "incredibly savvy" and taking it upon themselves to find solutions to the challenges they face, Dr Stephenson said.
"Young people are doing it for themselves."
Elin Charles-Edwards, a senior lecturer in population geography from the University of Queensland, said there were various issues arising as population growth plays out across the region.
For most, climate change and a rapidly urbanising population are among the biggest challenges.
There is also the issue of employment and ensuring there are enough job opportunities to avoid a "youth bulge".
"Where you have lots of young people educated but they just can't actually create meaningful livelihoods," she said.
"It's a big challenge."
There is currently a demographic dividend where there is a large working age population, "which is really good for economic productivity".
Countries have an opportunity to make the most of their record numbers of youth to boost the economy before they become middle-aged.
The majority of countries across South-East Asia are experiencing a drop in fertility, so they need to focus on mitigating the decline and educating young people to manage national development, Dr Charles-Edwards said.
"You need to make sure that babies are surviving into adulthood, so targeting life expectancy," she said.
"So, improving maternal and child health.
"Then the next big thing is to make sure you're educating your youth population."
Finding a voice amid repression
Decent work and unemployment are among the main issues highlighted by the ASEAN Youth Forum, alongside topics such as the climate emergency, sex education, politics and democracy.
Young people are also becoming increasingly worried about human rights violations and growing repression across the region.
With digital authoritarianism on the rise, Fatimah Zahrah, the ASEAN Youth Forum lead coordinator, is concerned about freedom of expression in both physical and digital spaces.
"Some governments can put you in jail because you said something that offends them," she said.
This is particularly concerning in Myanmar where the military junta has introduced surveillance and information control that UN rights experts have labelled a "digital dictatorship".
The ASEAN Youth Forum movement creates spaces for young people to raise awareness of their rights and build solidarity across the region.
Ms Zahrah said being able to share knowledge and experiences was crucial.
"For example, when we talk about freedom of expression, the participants from Indonesia, Malaysia, Myanmar and many countries from South-East Asia will share similar versions of repression," she said.
"Sometimes it's good to feel like we are not alone."
Growing up as part of the Ahmadiyah Muslim minority in Indonesia, Ms Zahrah said she wasn't aware of her rights.
This is part of the reason the 31-year-old became involved in the youth forum.
"You should at least know when your rights are being violated," she said.
"For me, it was empowering to gain that knowledge about my rights so then I knew what I could do."
Dr Stephenson said in Myanmar and other countries across the region, there has been a "we will not accept authoritarianism streak" among young people.
"There's a collective action and mobilisation happening within young people who are connected now beyond their borders with the internet and everything else," she said.
"So perhaps what certain regimes could have gotten away with in the past, there's a bit more regional solidarity."
Ms Zahrah said building spaces for solidarity for young people at a cross-border and international level was leading to a "new and emerging youth-led purpose".
"They are gaining awareness and participating in protests, whether it's spiritually or on the streets."
