Can my parents claim me as a dependent if I am married? How can I make sure they will be able to?

My husband and I are in college and got legally married in December of last year. Our parents do not know that we are legally married until our wedding ceremony. Neither of us make a substantial income, and from what I understand, our parents would still be able to claim us as dependents if we file as married filing separately. Is that correct? What is the limit on our personal income where our parents can still claim us as dependents? What do we need to be careful about to both maximize our returns and file legally without interfering with our parents' taxes?