Getting married at a young age won't make you poor.Having kids at a young age will make you poor for sure.
I don't know about your country,but rising a kid from it's birth to the age of 18 costs more than 150,000 USD in the USA.The cost might be lower in the other countries,but it's still a significant amount of money.
I agree getting married early does not mean that you will be poor, the fact that you have another person protecting your back and they have you too to protect theirs is great but adding kids to the mix will surely make you poor since in the economy of today you need a lot of preparation to get to the highest paid jobs, something that is very difficult if you have to feed a big family.