This study aims to compare two commonly used hormone treatments for women undergoing IVF. All participants will receive a stimulation protocol that includes dydrogesterone, a medication used to safely control natural hormone surges during treatment. The study will observe women who are treated either with recombinant FSH alone or with a combination of recombinant FSH and recombinant LH-both routinely used options in our clinic.

Investigators will prospectively monitor how these treatments affect the growth of ovarian follicles, the number of mature eggs collected, the quality of developing embryos, and early pregnancy outcomes. No additional procedures or medications will be required beyond standard IVF care. The goal is to better understand whether adding recombinant LH provides any measurable benefit in dydrogesterone-based PPOS cycles.

This prospective observational study aims to evaluate how two routinely used gonadotropin strategies influence ovarian response and reproductive outcomes in women undergoing IVF treatment with a dydrogesterone-based Progestin-Primed Ovarian Stimulation (PPOS) protocol. In standard clinical practice, ovarian stimulation may be performed using recombinant FSH alone or a combination of recombinant FSH and recombinant LH. Both approaches are already used in daily care, and the choice of regimen is determined by the treating physician according to individual patient characteristics. The study does not assign treatments; instead, it observes and compares outcomes in patients receiving these medications as part of routine management.

Dydrogesterone is administered from Day 2 of the cycle to prevent premature LH surges, allowing controlled follicular growth. Participants will undergo regular ultrasound monitoring and bloodwork as part of their usual IVF treatment. When appropriate follicular maturation is achieved, final oocyte maturation will be triggered, followed by oocyte retrieval according to standard clinical protocols.

The primary focus of this study is to compare the number of mature (MII) oocytes obtained between the two gonadotropin regimens. Secondary outcomes include the number of good-quality blastocysts, implantation rate, and ongoing pregnancy rate, which together provide a comprehensive assessment of IVF success. Additional stimulation characteristics-such as follicle growth patterns, estradiol and LH levels, total gonadotropin dose, and duration of stimulation-will also be documented to explore differences in cycle dynamics.

No extra medications, procedures, or interventions will be required beyond routine IVF care. All data will be collected prospectively and analyzed to determine whether adding recombinant LH offers measurable clinical advantages compared with recombinant FSH alone in dydrogesterone-PPOS cycles.

Inclusion Criteria:

• Women aged 20 to 43 years.
• BMI < 30 kg/m².
• AMH > 1 ng/mL.
• Undergoing IVF/ICSI treatment with a dydrogesterone-based PPOS protocol.
• Women with regular menstrual cycles or clinically acceptable cycle pattern for stimulation.
• Ability to provide informed consent and comply with study procedures.
• Presence of at least one ovary and eligibility for controlled ovarian stimulation

Exclusion Criteria:

• Cycle cancellation due to lack of viable embryos.
• Prior or planned PGT-A in the same cycle.
• Adenomyosis diagnosed by ultrasound or MRI.
• Uncorrected uterine anomalies (e.g., bicornuate, unicornuate, didelphys uterus).
• Presence of hydrosalpinx.
• Use of oral contraceptives or luteal-phase estradiol within 3 months before stimulation.
• Refusal or inability to provide informed consent.
• Severe systemic disease or contraindication to ovarian stimulation.
• Prior bilateral oophorectomy

Participants will be selected from women seeking infertility treatment at a fertility clinic and undergoing in-vitro fertilization (IVF) with controlled ovarian stimulation. This population typically consists of reproductive-age women who have difficulty achieving pregnancy and require assisted reproductive technologies. Eligible patients are generally healthy enough to undergo ovarian stimulation, have adequate ovarian reserve (AMH > 1 ng/mL), and meet age and BMI criteria for standard IVF care. Women in this group routinely receive dydrogesterone-based PPOS protocols as part of their clinical treatment, and the choice of gonadotropin regimen (rFSH alone or rFSH+rLH) follows routine medical practice. This population reflects real-world patients commonly treated in IVF programs

Individual participant data will not be shared because the study involves sensitive reproductive health information and data are collected solely for clinical and research purposes within the center. Only aggregated, de-identified results will be reported in publications.

Supporting Documents to Be Shared: None.