Baby had prolapsed sac and died in birth. Any way to prevent in future?

Incompetent cervix. What you seem to be describing is what happens when the fetal material in the womb slides out of the cervix because the opening is not able to hold it in. This condition, an incompetent cervix, may be treated by the OB by inserting a strong band around the cervix like a purse string. This is drawn to a certain tightness and left in place until u are far along enough to have a nl delivery.