This is undoubtedly the most classic and often the most reliable early sign of pregnancy. When an egg is fertilized, the body starts producing human chorionic gonadotropin (hCG), an essential hormone that stops the menstrual cycle to protect and support the embryo’s development.

• Other possible causes: Stress, travel, sudden weight changes, intense exercise, or certain medical conditions can also cause delays.
• Implantation bleeding: Some women may experience very light pinkish or brownish bleeding when the embryo attaches to the uterine wall.

If you have a regular cycle and notice a delay, this is the strongest reason to take a pregnancy test.