Menstruation occurring earlier than expected might lead to infertility. Generally, if a woman's period occurs every 20 days or so, it may be indicative of a shortened luteal phase, which can impact pregnancy. If menstruation consistently occurs earlier, it can affect ovulation and the development of the endometrium, which is disadvantageous for conception. If the advance in timing is significant, it usually suggests poor ovarian function, which can impact the development of follicles and the endometrium, thereby affecting pregnancy. If the cycle is very regular and involves normal follicles, the possibility of pregnancy cannot be ruled out. It is recommended to maintain a good mood and ensure adequate rest.