They are not being discriminated against. They are not forced to earn the minimum wage, they are free to apply for jobs that will pay them more than that. And they are not forced to have a child either!
If two 19 year olds on low income decide to get married and have a child, that is their decision. It is up to them to plan their lives and not bring a child into it unless they can bloody afford it! That is where this country has gone down the pan with people who just think that someone else ought to support them and pay for their choices.
Yes, some people make mistakes, and some people get left in the shit, which is why we have a benefits system in place, to help those who are in need. Also, people with children, on a low income are entitled to help, with tax credits.