38920
During the early stages of pregnancy , since the placenta is not yet formed , there is no mechanism to protect the embryo from the deficiencies which may be inherent in the mother 's circulation .
 None
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
 Entities:  
Answer:
 None