Psychological factors behind Premature Ejaculation (PE) Some doctors believe that sexual experience at an early age may set up a pattern like urgency to reach climax or guilty feelings that increase the tendency to rush through sexual encounters.
These patterns can be difficult to change later in life.
The other factors that can contribute in causing PE include:

• Personal relationship problems
• Problems related to work, home or money
• Feeling of urgency to reach the climax during early sexual encounters may set the pattern for premature ejaculation
• Men suffering from erectile dysfunction have a greater chance to have PE problems
• Feelings of guiltiness, despair, or fretfulness

Biological factors behind PE A number of biological factors may contribute to PE, including:

• Abnormal hormonal levels
• Infection and Inflammation of the prostate or urethra
• Inherited traits
• Abnormal levels of brain chemicals known as neurotransmitters
• Certain thyroid and vascular problems
• Abnormal reflex activity of the ejaculatory system

In rare cases, PE can be caused by:

• Any damages to nervous system due to surgery or trauma
• Drug called trifluoperazine (Stelazine) is used to treat anxiety and other mental health problems, sudden withdrawal from these kinds of narcotics may result in Premature ejaculation.
  

However, experts think that it's mostly a biological cause behind primary prejaculation.
Prejaculation have occasional problems that are not persistent or not accompanied by marked distress or interpersonal difficulty do not qualify for the diagnosis of PE.
A few things that must be considered are the individual's age, overall sexual experience, latest sexual activity, and the novelty of the partner.