I believe the answer is: amnion
Amnion refers to the outer membrane covers and protected the embryo when it first formed. This memberane help the fetus to protect itself from the impact that experienced by the mother in her environment (such as fallen to hard floor, being bumped when walking, etc)
Marsha is 6 months pregnant and she has just slipped and fallen on her hardwood floor. If Marsha's amnion is working properly, her baby will likely not suffer any damage from her fall.
