Which hormone increases during the follicular phase of the menstrual cycle to prepare the uterus for ovum fertilization?

• A. Progesterone
• B. Estrogen
• C. Testosterone
• D. Luteinizing hormone

Answer: (B)

The hormone that increases during the follicular phase of the menstrual cycle and prepares the uterus for ovum fertilization is estrogen. In the early part of the cycle, several follicles in the ovaries begin to mature under the influence of follicle-stimulating hormone (FSH). As these follicles develop, they produce increasing amounts of estrogen.

Estrogen plays a crucial role in thickening the endometrium (the lining of the uterus) in preparation for a potential implantation of a fertilized ovum. This thickening is essential to create a suitable environment for an embryo should fertilization occur. Elevated estrogen levels also trigger a surge in luteinizing hormone later in the cycle, leading to ovulation.

Other hormones listed do not fulfill this specific role in the follicular phase. For example, progesterone levels increase after ovulation during the luteal phase, primarily to sustain the uterine lining if fertilization occurs. Testosterone is not a primary hormone involved in the menstrual cycle, and while luteinizing hormone is important for triggering ovulation, it does not increase during the follicular phase but rather reaches a peak just prior to ovulation. Therefore, estrogen is the key hormone in this stage of the menstrual cycle.