What Causes Black/brown Moles On The Body?

hi doctor i live in pakistan .im female age now 33,weight is 53kg and height is 5/5.im married and have 2 daughters.i dont use any medicine.im noticing from last 5 months that some light brown and black moles in small sizes are appearing on my body and face day by day,im worried now ,im not even pregnant now ,plz tell why they are coming.