What can be one of the earliest signs indicating pregnancy?

A missed menstrual period is widely recognized as one of the earliest and most significant signs of pregnancy. This occurs because, during pregnancy, the hormonal changes initiated by conception inhibit the normal menstrual cycle, preventing ovulation and menstruation from happening. For many individuals, a missed period serves as a prompt to take a pregnancy test and is often the first indication that they may be expecting.

In contrast, increased appetite can occur at various times and may not necessarily indicate pregnancy. Regular menstrual cycles would suggest that a person is not pregnant, as the absence of menstruation is a hallmark sign of pregnancy. Severe headaches can be caused by numerous factors unrelated to pregnancy, such as stress or dehydration, making them a less specific sign of a potential pregnancy. Thus, the missed menstrual period remains the key early indicator that prompts further investigation into the possibility of pregnancy.