So I know not to worry but I’m more than freaking out.. I’m at my dr appt 15 weeks so many days and…

So I know not to worry but I’m more than freaking out.. I’m at my dr appt 15 weeks so many days and they said they want me to take the triple screen test..? I never took that test during my first pregnancy.. why with this one? Could they have seen something during blood work?