What Is a Frozen Embryo Transfer (FET)

FET refers to thawing embryos that were cryopreserved in a previous IVF cycle and then implanting them into the uterus. Thanks to vitrification technology , modern embryo thaw survival rates now exceed 95% . Many studies — including ESHRE data — show that FET live birth rates are no worse than, and can even surpass, those of fresh embryo transfers, making FET the preferred choice for a growing number of families.

Frozen vs Fresh: Why More People Are Choosing Frozen

  • It avoids the adverse effects of high stimulation-phase estrogen on endometrial receptivity.
  • It significantly reduces the risk of ovarian hyperstimulation (OHSS), especially for high-risk patients.
  • It allows PGT-A screening before scheduling a single elective transfer, improving the implantation rate per attempt.
  • It gives the body ample recovery time, bringing endometrial conditions closer to the natural physiological state.

Endometrial Preparation Protocols

  • Natural cycle: Suitable for women with regular menstrual cycles and spontaneous ovulation. Transfer is scheduled after monitoring natural ovulation — less medication, closer to the body’s natural physiology.
  • Medicated cycle (hormone replacement): Oral or vaginal estrogen thickens the endometrium, followed by progesterone to trigger conversion. The timing is controllable and well suited to those with ovulatory disorders or a thin endometrium.
  • The doctor determines the implantation “window” based on endometrial thickness (ideally ≥7–8 mm ) as well as its shape and blood flow.

What Happens on FET Day

Embryo thawing → survival and grading assessment → just like a fresh transfer, the embryo is placed into the uterine cavity via a soft catheter. The process is painless, requires no anesthesia, and takes about ten minutes in total.

Success Rates and Cost

The single-attempt live birth rate of FET is closely tied to embryo quality and maternal age, with blastocyst-stage freezing offering better outcomes. Because the stimulation and egg retrieval steps are skipped, the cost of an FET cycle is significantly lower than that of a brand-new retrieval cycle — making it highly cost-effective.

Post-Transfer Precautions

Continue progesterone support until weeks 8–10 of pregnancy; maintain moderate activity and a balanced diet; avoid frequent anxiety-driven pregnancy testing, and confirm with a unified blood test after 14 days . If you experience mild bloating or a small amount of brown discharge after transfer, it is usually nothing to worry about — simply observe as your doctor advises.

Common FET Questions

  • How long should I rest? Daily activities are unrestricted after transfer; just avoid overexertion. Prolonged bed rest is actually counterproductive.
  • Can the embryos be “damaged” by freezing? Vitrification cools at ultra-fast speeds, causing minimal cellular damage, with thaw survival rates above 95% .
  • How many FETs are appropriate? Embryos from the same batch can be transferred multiple times, until they are used up or pregnancy is achieved — economical and flexible.

Have frozen embryos and want to plan your next transfer? The International Department of Shenzhen Luohu Hospital uses advanced vitrification technology. A complete IVF cycle costs approximately $4,500–6,000 , which is 60–70% lower than in the United States. Book a consultation: /consultation/, or reach us on WhatsApp: https://wa.me/8618886468446