What could be the reason for not having a menstrual period but also not being pregnant?

The absence of menstruation without pregnancy can be caused by various factors, mainly including:

1. Endocrine disorders: Prolonged熬夜 (staying up late), excessive mental stress, or irregular lifestyle may lead to hormonal imbalances in the body, resulting in menstrual irregularities.

2. Intrauterine adhesions: Certain factors such as uterine surgeries or severe cervical inflammation may damage the basal layer of the endometrium, leading to intrauterine adhesions and preventing normal menstrual flow.

3. Polycystic ovary syndrome (PCOS): This is a common endocrine and metabolic disorder, with main symptoms including menstrual abnormalities, hirsutism (excessive hair growth), and infertility.

4. Other pathological factors: Conditions such as premature ovarian failure or cervical adhesions may also cause amenorrhea.