The goal of this observational study is to compare laboratory and ultrasound findings between letrozole-resistant and letrozole-sensitive PCOS patients in Egypt. The study will include women aged 18-40 years diagnosed with PCOS based on the Rotterdam criteria, who are undergoing ovulation induction with letrozole for the first time.

The main questions it aims to answer are:

What are the baseline laboratory and ultrasound differences between letrozole-resistant and letrozole-sensitive PCOS patients? What factors can predict letrozole resistance in PCOS patients? Researchers will compare letrozole-resistant and letrozole-sensitive PCOS patients to determine whether specific laboratory markers and ultrasound findings can predict resistance to letrozole.

Participants will:

Undergo baseline clinical, laboratory, and ultrasound assessments before starting letrozole treatment.

Receive letrozole treatment with dose escalation up to 7.5 mg/day over a maximum of three cycles if ovulation is not achieved.

Be monitored through serial transvaginal ultrasounds to assess follicular development.

Have ovulation confirmed via mid-luteal serum progesterone levels. The study aims to improve the understanding of predictors of letrozole resistance to guide personalized ovulation induction strategies in PCOS patients.

Inclusion Criteria:

• Women aged 18-40 years.
• Diagnosis of PCOS based on Rotterdam criteria.
• No prior ovulation induction with letrozole.
• Willing to follow the treatment protocol and attend follow-up visits

Exclusion Criteria:

• Infertility due to other causes such as tubal obstruction or male factor infertility.
• Previous ovarian surgery or use of medications that could influence ovulation.
• Comorbidities such as uncontrolled diabetes, hyperprolactinemia, or thyroid dysfunction.

This study will include female participants only, as it focuses on women diagnosed with polycystic ovary syndrome (PCOS) who are undergoing ovulation induction with letrozole for infertility treatment. Male participants are not eligible for this study.

The study will include women diagnosed with polycystic ovary syndrome (PCOS) based on the Rotterdam criteria, who are seeking infertility treatment and undergoing ovulation induction with letrozole for the first time. Participants will be women aged 18-40 years, recruited from the outpatient clinic at Al-Hussein University Hospital, a tertiary healthcare center in Egypt. All participants will undergo a comprehensive baseline assessment, including clinical evaluation, laboratory investigations, and transvaginal ultrasound before starting letrozole treatment. The study aims to identify potential predictors of letrozole resistance by comparing baseline characteristics between women who respond to treatment and those who do not.

The study investigators will share de-identified individual participant data (IPD) related to baseline laboratory and ultrasound findings, ovulation outcomes, and relevant clinical parameters. The shared dataset will exclude any personally identifiable information to ensure participant confidentiality.

The data will be available six months after study completion and will remain accessible for a period of five years.

Researchers and qualified investigators may request access to the dataset for scientific and academic purposes. Requests must be submitted to the corresponding author via email and include a research proposal outlining the intended use of the data. Access will be granted upon approval by the study team, and data users must agree to a data use agreement ensuring confidentiality and ethical use of the shared information.