Which hormone is primarily responsible for the regulation of the menstrual cycle?

• A. Estrogen
• B. Testosterone
• C. Progesterone
• D. Oxytocin

Answer: (A)

The hormone primarily responsible for the regulation of the menstrual cycle is estrogen. Estrogen plays a critical role in the menstrual cycle, particularly during the follicular phase, where it is produced by the developing follicles in the ovaries. This hormone promotes the growth and thickening of the endometrial lining in preparation for potential implantation of a fertilized egg.

Estrogen also influences the timing of the luteinizing hormone (LH) surge, which triggers ovulation. After ovulation, progesterone, another key hormone, works alongside estrogen to maintain the uterine lining, but it is estrogen that initiates and regulates the early phases of the cycle. Hence, while both estrogen and progesterone are essential for menstrual cycle regulation, estrogen is the primary hormone in the initial regulation and preparation of the menstrual cycle phases.