Faking a pregnancy is a complicated deception often driven by desperation and fear. A character in this situation may want to manipulate a partner into commitment, meet societal expectations, or gain financial or emotional support. Whatever the motivation, this secret has a finite shelf-life, at which point their deception will be discovered or the character will have to lie again to terminate the pretend pregnancy.

Personal or Private (primary), Betrayals and Violation of Trust, Family and Relationships

BEING PREGNANT, FAKING AN ILLNESS

ABANDONMENT, BEING LABELED, BEING PITIED, BETRAYAL, CONDITIONAL LOVE, HAVING NO PURPOSE, HUMILIATION, INFIDELITY, ISOLATION, LETTING OTHERS DOWN, LOSING FINANCIAL SECURITY, LOSING THE RESPECT OF OTHERS, NEVER FINDING HAPPINESS, NOT BEING IN CONTROL, REJECTION

Loved ones becoming deeply invested in the idea of the baby, creating deep guilt and shame for the character
Feeling compelled to continue the lie longer than they initially planned
The pregnancy becoming part of their identity
Missing chances to build intimacy with a partner because they must protect the secret 
Escalating mental health issues, such as narcissism, unresolved trauma, or plummeting self-esteem, causing instability and further poor decision-making

Changing their diet or lifestyle to mimic that of a pregnant woman's
Employing prosthetic aids or props (a fake baby bump, maternity wear, a falsified pregnancy test, etc.) to support the lie
Faking morning sickness and other symptoms of pregnancy
Fabricating reports from prenatal visits 
Creating conflict or emotional barriers to discourage others from asking probing questions
Avoiding physical intimacy (to hide the lack of physical changes)

Making excuses to avoid medical appointments
Exhibiting a lack of knowledge about pregnancy milestones and expectations