58 years old woman still gets pregnant?!!

Guys i don't know if you believe this but when i go to school yesterday i really surprise mother and daughter are classmate together in vocational course, her mother is already 75 years old and her daughter is 17 years old, if you calculate this lady gets pregnant at the age of 58, it is possible to happen? But its really true, i just talk to them yesterday 75 years old mother and 17 years old daughter. would somebody help me to explain this kind of situations? Happy mylotting to all!!!