A 28-year-old woman from Delhi presents with primary infertility of 3 years duration. Her husband's semen analysis is normal. She has regular menstrual cycles of 28 days. Transvaginal ultrasound shows normal ovarian morphology. Serum progesterone on day 21 of the cycle is 2 ng/mL (normal >5 ng/mL). FSH and LH are normal. What is the most appropriate first-line ovulation induction agent for this patient?

Explanation

## Clinical Presentation Analysis This patient has **anovulation with normal FSH/LH levels** (likely WHO Group II anovulation). The low progesterone on day 21 confirms absent or inadequate ovulation despite regular cycle length. ## First-Line Ovulation Induction Agent **Key Point:** Clomiphene citrate is the first-line agent for WHO Group II anovulation (normal FSH/LH, normal/elevated estrogen). **High-Yield:** Clomiphene citrate mechanism: - Selective estrogen receptor modulator (SERM) - Blocks negative feedback of estrogen on hypothalamus and pituitary - Increases endogenous FSH and LH secretion - Stimulates follicle development - Success rate: 70–80% ovulation, 40–50% pregnancy ## Comparison of Agents | Agent | Indication | First-Line? | Notes | |-------|-----------|------------|-------| | Clomiphene citrate | WHO II anovulation, PCOS | **YES** | Oral, cost-effective, fewer injections | | Letrozole | PCOS, clomiphene resistance | No (second-line) | Aromatase inhibitor; emerging evidence | | Gonadotropins | WHO I/III, clomiphene failure | No (second-line) | Expensive, requires monitoring, OHSS risk | | GnRH agonist | Endometriosis, not anovulation | No | Wrong indication entirely | ## Dosing Protocol **Key Point:** Standard clomiphene citrate protocol: - **Dose:** 50 mg daily × 5 days (can escalate to 100–150 mg if no response) - **Timing:** Day 3–7 or day 5–9 of menstrual cycle - **Monitoring:** Transvaginal ultrasound on day 10–12 to assess follicle size - **Ovulation trigger:** hCG 5000–10,000 IU when lead follicle ≥18 mm **Clinical Pearl:** Clomiphene works best in patients with intact hypothalamic-pituitary-ovarian (HPO) axis and adequate endogenous estrogen production. ## Why This Patient Qualifies - Normal FSH/LH → HPO axis intact - Normal ovarian morphology → good ovarian reserve - Regular cycles → some endogenous estrogen - **Conclusion:** Clomiphene is ideal; no need for expensive gonadotropins as first-line.