What is a probable sign of pregnancy?

A positive pregnancy test is considered one of the probable signs of pregnancy because it indicates the presence of human chorionic gonadotropin (hCG) in the woman's urine or blood. This hormone is produced early in pregnancy by cells that develop in the placenta and can be detected shortly after implantation of the embryo. A positive result from a reliable test is a strong indicator of pregnancy and is usually confirmed through clinical assessments.

In contrast, the absence of a menstrual cycle can sometimes be misleading as it can occur due to various factors unrelated to pregnancy, such as stress, hormonal imbalances, or other medical conditions. Weight loss is typically not associated with pregnancy and may indicate other health issues. Unusual cravings can occur during pregnancy, but they are not a definitive sign, as they can happen for various reasons even in non-pregnant individuals. Thus, the positive pregnancy test stands as the most reliable probable sign of pregnancy among the options given.