If these fetal vessels rupture the bleeding is from the fetoplacental circulation, and fetal exsanguination will rapidly occur, leading to fetal death. It is thought that vasa previa arises from an early placenta previa. As the pregnancy progresses, the placenta tissue surrounding the vessels over the cervix undergoes atrophy, and the placenta grows preferentially toward the upper portion of the uterus.
If fetal vessels rupture, bleeding originates from the fetoplacental circulation, leading to rapid fetal death. Vasa previa is thought to be a consequence of early placenta previa. As pregnancy progresses, the placental tissue surrounding the vessels over the cervix shrinks, and the placenta grows towards the upper portion of the uterus.