Why is the prenatal period the most crucial period in development?

A period between conception till birth is called a prenatal period. It is the most crucial period in development due to the following factors:

• Heredity serves as the foundation for later development. 
• Favourable conditions in the mother’s womb can foster the development of hereditary potentials while unfavourable conditions can block their development. 
• Sex determination takes place during the first three months of life. 
• Proportionally faster growth and development take place during the prenatal period as compared to an individual’s entire life. 
• Failure to take proper care of the mother may lead to physical and psychological hazards to the unborn child