For a woman having a regular monthly cycle, the earliest and most reliable sign of pregnancy is a missed period, or sometimes women who are pregnant have a very light period, losing only a little blood. Other signs are:

 
• Feeling sick, not necessarily in the morning, but at any time.  
• The breasts may become larger and tender. Veins may become prominent and nipples may darken and stand out.  
• Increased frequency in passing urine.  
• Tendency for constipation.  
• Tiredness.  
• An increased vaginal discharge without any associated complaint.  
• A metallic taste in the mouth.  
• Dislike for certain things like tea or coffee or fatty foods.  
• Increased liking for certain things like spicy foods.

Pregnancy test can be carried out on urine samples, as early as from the first day of a missed period-that is, about fourteen days after the conception.
A positive test result is almost definitive of pregnancy. If the test is negative, it is less reliable. It can be repeated after a week, or a doctor can be consulted.