single umbilical artery

had our 19 week analomy appointment today. all is well, though doctor informed us that baby only has one artery instead of two in its umbilical cord. anyone else experience this? 'Dr Google' is terrifying. I know we'll have extra growth scans, and I selected to have a fetal electrocardiogram. I am considered advanced maternal age, so I had genetic counseling as well-- all tests for down, cystic fibrosis, etc came back negative as well. just trying to calm my nerves at this point.