Follicular Phase
Follicular Phase is the first half of the menstrual cycle, beginning with the onset of menstruation and ending with ovulation. Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) drive the recruitment and maturation of ovarian follicles during this phase. A single dominant follicle produces rising estradiol, which drives proliferation of the endometrium and triggers the LH surge that causes ovulation.
Unlike the luteal phase, which is relatively fixed at approximately 14 days, follicular phase length is variable. Most cycle-to-cycle variation in total cycle length originates here.
In Restorative Reproductive Medicine, the follicular phase receives detailed clinical investigation. NaProTECHNOLOGY and FEMM practitioners use cervical mucus observations, serial hormone profiles, and follicular ultrasound to identify follicular phase deficiency: short or hypoestrogenic phases and impaired follicular maturation. Hilgers describes follicular phase defect as a distinct, often-overlooked counterpart to luteal phase defect. RRM evaluation for follicular phase defect may include assessment for ovulation induction or estradiol support, depending on clinical findings.
This content is for educational purposes only and does not constitute medical advice. Consult an RRM clinician or healthcare provider for guidance specific to your situation.