I have missed my period for the first time i'm 5 years and it was due to pregnancy. should i be worried?

Not clear: It's not clear what your question is. It's normal to miss a period due to pregnancy, it's one of the definitions of pregnancy. If this wasn't your question, consider asking again with clarification.

Agree w Dr. Van Dis: It you meant to say it was not due to pregnancy then the following applies. Reasons for missed / late period include: an anovulatory cycle in which no egg is released, marked v or ^ in weight; eating disorder; over-exercising (endurance athletics), travel, significant illnesses, oral contraceptives ; other meds, illegal drug use, breast feeding, hormone imbalances and medical problems (i.e., pcos).