Must I offer expiation or fast after the death of the twins I bore prematurely?

We ask God to make these two children a veil for you from the Fire; because of the Prophet's (peace and blessings of Allah be upon him) saying: "There is no woman among you who loses three of her children except that they will be a veil for her from the Fire." A woman among them asked, "O Messenger of Allah, or two?" He repeated it twice, then said, "And two, and two." You are not required to do anything simply due to the anxiety you felt when you learned you were pregnant with twins, as you did not cause a miscarriage.