💊 Emergency Contraception Timing-Window Simulator

Unprotected Intercourse — The Timing Clock Starts Now

Every EC decision is measured from a single starting point in time.

• 2 main: EC options available (LNG and UPA oral pills)
• Cu-IUD: Backup option (most effective, up to 5 days)
• 0–120h: Decision window (sooner is always better)
• OTC / Rx: Access (varies by drug and region)

Why timing matters

Placeholder: earlier EC use consistently improves outcomes.

Hours Since Intercourse — Racing the Effectiveness Curve

Every EC method loses effectiveness as hours accumulate.

• <24h: Ideal window (highest efficacy for both drugs)
• 72h: LNG label limit (FDA-approved window)
• 120h: UPA label limit (FDA-approved window)
• Declining: Efficacy trend (monotonic with hours elapsed)

Countdown dynamics

Placeholder: the timeline curve shows falling protection hour by hour.

Levonorgestrel — Fast-Acting but Time-Sensitive

LNG delays ovulation but loses power quickly after intercourse.

• Delays LH surge: Mechanism (blocks/delays ovulation)
• ~95%: Peak efficacy (within first 24 hours)
• Reduced: BMI sensitivity (less effective at higher BMI)
• OTC: Availability (no prescription needed, most regions)

LNG decay profile

Placeholder: steep drop-off in protection after about 72 hours.

Ulipristal Acetate — A Longer, Flatter Window of Protection

UPA blocks ovulation closer to the LH peak, extending usefulness.

• Progesterone modulator: Mechanism (blocks LH surge later too)
• ~85–88%: Peak efficacy (sustained across 5 days)
• More robust: BMI sensitivity (than LNG at higher BMI)
• Rx only: Availability (in most regions)

UPA decay profile

Placeholder: efficacy declines gradually, staying useful through day 5.

Menstrual Cycle Phase — Ovulation Timing Shapes Real Risk

Baseline pregnancy risk without EC peaks near ovulation.

• ~6 days: Fertile window (ending at ovulation)
• Day 0: Peak risk day (ovulation day, relative)
• Early/late cycle: Low-risk phase (far from ovulation)
• 28 days: Cycle length used (simplified average model)

Cycle-risk overlay

Placeholder: risk rises and falls with proximity to ovulation.

Placeholder: EC choice should still favor speed over cycle-day precision.