My baby always cries before she goes to bed. what causes her to scream and cry herself to sleep?

Age dependent: It depends on the age of the baby. Small babies can have reflux after they eat if put to bed directly after feeding. Also some babies cry a lot and this is called colic and goes away over time. If she is older then she could have separation anxiety from being away from you which scares here and finally this could be behavioral and she wants to stay up and be with the family