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Ryu Yi-seo, wife of Shinhwa member Junjin, has shared her journey toward embryo transfer six years into their marriage, including a platelet-rich plasma (PRP) procedure in which plasma extracted from her own blood was injected into her uterus ahead of the transfer.

Ryu recently posted a video on her YouTube channel showing herself and Junjin visiting a fertility clinic. After the appointment, she said an ultrasound had shown her uterus was in good condition and that she would be attempting an embryo transfer for the first time.

Two days before the transfer, she underwent a PRP procedure. "They draw my blood, separate the growth factors and inject them into the uterus," she explained, adding that she experienced mild discomfort similar to menstrual cramps rather than sharp pain.

After having two embryos transferred, Ryu said she felt nervous about being at a crossroads — the procedure could lead to a pregnancy or it might not. "Fortunately, they said my uterine lining was in good condition," she added.

In in vitro fertilization (IVF), eggs and sperm are fertilized outside the body and the resulting embryos are transferred into the uterus. The chances of a successful pregnancy depend on multiple factors beyond embryo quality, including the state of the uterine lining, the woman's age and the outcomes of any previous treatment.

Checking the uterine lining before embryo transfer does not guarantee implantation

Assessing the uterine lining by ultrasound before an embryo transfer is standard practice in fertility treatment.

The endometrium is the tissue where an embryo implants. Its thickness and shape change throughout the menstrual cycle, and the lining must be in a receptive state at the time of transfer. For frozen embryo transfers, the lining is prepared either by working with the body's natural ovulation cycle or by administering estrogen and progesterone.

Endometrial thickness measured by ultrasound is one of several reference points used when deciding whether to proceed with a transfer. However, a lining above a certain thickness does not guarantee pregnancy, nor does a thin lining make pregnancy impossible on its own. Chromosomal status and developmental stage of the embryo, along with the condition of the uterus, are among the many factors involved in implantation.

The transfer itself is performed by threading a thin catheter through the cervix and placing the embryo inside the uterus. The procedure is typically brief enough that anesthesia is not required, and it places considerably less physical strain on the body than egg retrieval.

There is a common belief that patients must rest in bed for an extended period after the transfer, but this is not supported by medical evidence. Guidelines from the European Society of Human Reproduction and Embryology (ESHRE) do not recommend bed rest following embryo transfer. Multiple clinical trials have found no difference in pregnancy or birth outcomes between patients who resumed normal activity immediately after the procedure and those who remained lying down for an extended period.

Ryu's account that her doctor told her to go about her normal routine until the transfer is consistent with this approach.

PRP uses the patient's own blood — but its effect on implantation is still under study

The PRP procedure Ryu underwent before her transfer stands for platelet-rich plasma.

The process involves drawing the patient's own blood, then using centrifugation to isolate plasma with a high concentration of platelets. Platelets contain multiple growth factors involved in tissue repair.

PRP was first adopted in orthopedics and cosmetic dermatology. In fertility treatment, researchers have been studying intrauterine PRP injections for patients with a thin endometrium or those who have experienced repeated implantation failure despite multiple embryo transfers.

Recent research has produced encouraging results. A 2026 meta-analysis of 10 randomized clinical trials involving 1,188 patients with repeated implantation failure found that clinical pregnancy rates and live birth rates were higher in the group that received PRP than in the control group.

However, the evidence is not yet strong enough to recommend PRP for all embryo transfer patients. A study published this year that re-analyzed 15 systematic reviews found a trend toward improved implantation and pregnancy rates, but concluded that the overall quality of the evidence was too low to support a definitive recommendation.

ESHRE, in its guidance reviewing add-on procedures used in fertility treatment, also said there is insufficient data to establish the safety and efficacy of intrauterine or intraovarian PRP, and advised against its routine use outside of rigorous research settings.

Because PRP is derived from the patient's own blood, the risk of an immune reaction is relatively low. However, the amount of blood used, the preparation method, the volume injected and the timing vary across studies, meaning the procedure has yet to be sufficiently standardized.

Does transferring two embryos improve success rates? Multiple pregnancy risks rise too

Ryu said two embryos were transferred during the procedure.

Transferring more than one embryo can increase the likelihood that at least one will implant, but if two or more implant simultaneously, the result is a multiple pregnancy — twins or more.

A multiple pregnancy carries implications beyond simply expecting two children. The risks of preeclampsia, gestational diabetes and preterm birth increase for the mother, and the fetuses face a higher likelihood of low birth weight and premature delivery.

For this reason, fertility medicine has been moving toward single embryo transfer — particularly for patients with a good prognosis — as a way to reduce these risks.

The American Society for Reproductive Medicine (ASRM) recommends transferring only one embryo when it has been confirmed to be chromosomally normal, regardless of the patient's age. Single embryo transfer is also strongly encouraged for women under 35 and for women aged 35 to 37 with a favorable prognosis. The decision to transfer more than one embryo is made by weighing the woman's age, the embryo's developmental stage and condition, and the results of any previous transfers.

A completed embryo transfer does not immediately reveal whether a pregnancy has occurred. Implantation must take place first, and the pregnancy hormone human chorionic gonadotropin (hCG) must rise to a detectable level before a blood test can confirm a pregnancy.

Waiting for results after the transfer, Ryu acknowledged the outcome was uncertain. "It may result in a pregnancy or it may not," she said. "What's left for us is to not be too disappointed."

Embryo transfer is a critical step toward pregnancy in the IVF process, but a favorable uterine lining or a completed transfer does not guarantee implantation. Add-on procedures such as PRP show promise in some research, but the evidence is not yet sufficient to confirm their effectiveness. Treatment decisions — including the number of embryos to transfer — should be made based on the patient's age, the cause of infertility, the condition of the embryos and the outcomes of any prior procedures.


rainbow@heraldcorp.com