What hormones dominate during the follicular phase of the menstrual cycle?

During the follicular phase of the menstrual cycle, estrogen and luteinizing hormone (LH) play pivotal roles. The follicular phase begins on the first day of menstruation and continues until ovulation, primarily focused on the development of ovarian follicles.

Estrogen is produced by the growing follicles and is crucial for regulating the thickening of the endometrial lining in preparation for potential implantation. It also participates in the feedback mechanism that influences the release of follicle-stimulating hormone (FSH) and LH from the pituitary gland.

Luteinizing hormone, while primarily associated with the later stages of the cycle and ovulation, does begin to rise as estrogen levels increase towards the end of the follicular phase, supporting the eventual surge that prompts ovulation. This hormonal interplay is essential for a healthy menstrual cycle, indicating the preparatory nature of this phase for subsequent ovulation and potential fertilization.

The presence of progesterone is minimal during the follicular phase, as it mainly rises during the luteal phase following ovulation. Therefore, the combination of estrogen and LH correctly captures the dominant hormonal influences in this initial phase of the menstrual cycle.