Dr. Varini N – Senior Consultant – Obstetrician & Gynecologist, Milann Fertility & Birthing Hospital, Kumarapark, Bangalore, says, “Your hormonal changes determine the timing of your periods. To put it simply, during the first two weeks of every month, the lining of the womb thickens due to the hormone oestrogen, which is produced by the ovaries. Progesterone preserves the uterine lining for the following two weeks after the ovulation phase to get ready for the entrance of a fertilised egg. However, if the pregnancy does not take place, progesterone levels fall significantly, which prompts the womb to lose its lining and signals the beginning of periods.”