I'm not sure of any particular signs but let's just say if your stomach gets slightly bloated it means either 1. You're pregnant or 2. Lay off the snickers. If you feel kicking in the stomach it can mean 1. You're pregnant or 2. You have a Rabbit living in your belly. The best chance is to check with a doctor regularly, avoid leaving it for periods of at least 9 months at a time because that is usually the time until a baby is due, so it's good to get check-ups occasionally.
Presumptive signs: Morning Sickness, Absence of period, fatigue, frequent urination and breast tenderness. Probable signs: + Pregnancy test, enlarged abdomen Positive signs: Fetal heart sounds can be heard and an ultrasound.