Menstruation started at age 13, first day was brown, and stopped by the second day.

A 13-year-old girl experiencing brown discharge on the first day of her period, followed by no flow on the second day, may be a normal occurrence, but it could also result from factors such as cold exposure or malnutrition. Appropriate measures should be taken based on specific circumstances. The detailed analysis is as follows:

1. Normal phenomenon

At age 13, girls are in a stage of physical development. At this time, ovarian and other reproductive organs have not yet fully matured. Menstrual cycles may be irregular and relatively short, which can lead to situations such as brown discharge on the first day of menstruation and no flow on the following day. This is considered normal. As the body continues to develop, menstrual cycles will gradually become more regular.

2. Cold exposure

If the body is exposed to cold during this time—particularly if the abdomen is subjected to cold temperatures—it may cause abnormal constriction of local blood vessels, leading to reduced menstrual flow or even amenorrhea (absence of menstruation). It is recommended to keep the abdominal area warm during menstruation and avoid contact with cold water or consuming cold foods.

3. Malnutrition

If a 13-year-old girl consistently consumes insufficient food, resulting in poor nutrition, the development of organs such as the ovaries may lack necessary nutritional support, leading to delayed development and causing this symptom. It is recommended to consume more foods rich in nutrients such as protein and fats, engage in appropriate physical exercise, and improve overall physical health.

In addition, this condition could also be caused by medication side effects, hormonal imbalances, or vaginitis. It is advisable to maintain a regular daily routine and avoid excessive fatigue to prevent abdominal discomfort.