For Frozen Embryo Transfer (FET), endometrial preparation requires estrogen and progesterone. Both have multiple delivery routes.
Estrogen — 4 Routes
- Oral (Progynova, Estrofem) — Convenient, widely used
- Sublingual — Bypasses first-pass metabolism, higher serum levels
- Vaginal — High uterine, low serum levels
- Transdermal patch (Climara, Estraderm) — Stable levels, fewer side effects
Progesterone — 3 Routes
- Vaginal (Crinone, Endometrin, Utrogestan) — Most popular, high uterine concentration
- Intramuscular (Progesterone in oil) — High serum, excellent efficacy
- Oral (Duphaston / dydrogesterone) — Convenient, Lotus I & II trials show non-inferiority to vaginal
Combination Strategies
Modern approach often combines vaginal + IM or vaginal + oral dydrogesterone for stable hormone levels.
Monitoring
Serum progesterone on day of transfer — if low, increase dose or change route.
