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.
It happens when getting married without proper planning. It doesn't matter at what you get married just make sure that you can adjust your life and have savings to start a new life. You cannot live happily and content when you do not know when to get financial to support everyday living. You have to prepare yourself for the big change in life.