Fetal blood loss in abnormal cord inseion is seen in:
Normally ,the umbilical cord is inseed at the centre of fetal surface of placenta. In Velamentous inseion of cord - the blood vessels are attached to the amnion, where they ratify before reaching the placenta. Whenever patient goes into labour and cervix dilates, there are chances of umbilical cord being injured leading to fetal blood loss. This is called as Bad pre. Ref: Datta Obs 9e pg 36,206.
Vasa pre
Decidua basalis
Battle Dore placenta
Succenturiate placenta
General obstetrics