Every question you ask can be matched with a suitable answer
Leave me a message
We take every suggestion of yours seriously
Wechat
Tan Xiaojun
·Senior reproductive medicine expert
·Postdoctoral fellow at Peking University
·PhD candidate at Xiangya School of Medicine, Central South
University
·Master’s tutor at Central South University
· Master's degree candidate in reproductive
medicine at the University of South China
· Professional training at Huazhong University
of Science and Technology and Tongji
Hospital Reproductive Center
Expertise:
diagnosis and treatment of infertility, first/second/third generation IVF (including
egg/sperm donation), microsperm retrieval, embryo freezing and resuscitation, artificial
insemination (including husband's sperm and sperm donation), paternity testing, chromosomal
disease
diagnosis, high-throughput gene sequencing, endometrial receptivity gene testing and other
clinical
technology applications. Many of these technologies are at the leading level both domestically
and
internationally.
Which is better, frozen embryo or fresh embryo? Frozen embryo transfer, fresh embryo transfer, IVF process, embryo freezing technology, choice of pregnancy assistance scheme, Kyrgyzstan test tube, difference between frozen embryo and fresh embryo.
Which is better, frozen embryo or fresh embryo? Six key differences explain the logic of helping pregnancy selection
After entering the test tube cycle, many people really start to feel anxious, not "do it or not", but a more detailed step: whether to choose fresh embryo transfer or frozen embryo transfer?
The essence of this problem is not simply to compare which one is "better", but to compare: * * which one is more suitable for the current physical condition, ovarian response, endometrial state and the overall rhythm of assisting pregnancy. * * From the medical point of view, both fresh embryos and frozen embryos belong to common clinical schemes, aiming at improving the chances of getting pregnant, but they do have obvious differences in time arrangement, endometrial preparation, risk control and applicable population.
Let's start with the definition. Fresh embryos, usually on the 3 rd or 5 th day after taking eggs, are directly transplanted back to the uterine cavity after being cultured in the current cycle; To freeze an embryo, the embryo is frozen first, and then the embryo is thawed and transplanted in a suitable period. According to the popular science data of American reproductive medicine, fresh embryo transfer usually occurs a few days after egg retrieval, while frozen embryo transfer is that the embryo has been formed and preserved before entering the uterus in another cycle.
Why do these two schemes coexist for a long time? The reason is simple: the clinical scenarios they serve are not exactly the same.
If the patient has a high hormone level and a strong ovarian response after ovulation induction, or the doctor is worried about ovarian hyperstimulation syndrome, frozen embryos are often more valuable, because it can delay transplantation and give the body a recovery window. ASRM's guidelines on OHSS prevention clearly point out that people with high AMH, PCOS and expected number of eggs are high-risk groups of OHSS, and clinical measures should be taken to reduce risks; And "whole embryo freezing" is one of the important risk control ideas in history.
On the contrary, fresh embryo transfer may be more in line with the demand of "shortening waiting time" if the number of eggs obtained by patients is small, the ovarian response is average and the synchronization of endometrium is acceptable. The patient-oriented data of SART/ASRM in the United States mentioned that in the analysis of large sample database, people with high reaction are more likely to benefit from the frozen embryo cycle; However, the low-response population with fewer eggs may have a higher chance of getting pregnant or live birth by fresh embryo transfer. It should be emphasized here that this is not an absolute conclusion, but a trend judgment based on stratified population analysis.
Therefore, the first level of judgment logic is not "fresh embryo is good or frozen embryo is good", but "what kind of people do you belong to".
For the following categories of people, frozen embryo transplantation is more often considered in clinic:
First, people with high estrogen level and strong ovarian response after ovulation promotion;
Second, there is OHSS risk, especially for people with high PCOS and AMH and more eggs;
Third, people who are going to do embryonic genetic testing, because waiting for the test results usually requires freezing the embryos first;
Fourth, when the endometrial conditions in the cycle are not ideal, such as thin endometrium, polyps found or the uterine cavity environment needs further evaluation. ASRM/SART popular science data clearly mentioned that worrying about the aggravation of OHSS, the unsynchronized embryo and endometrium caused by the increase of progesterone in the process of ovulation promotion, the planned embryo genetic test and the problems of endometrium are all important reasons for considering frozen embryos.
And fresh embryo transfer is more common in:
People who have relatively stable ovulation induction reaction, appropriate intima thickness and shape, no obvious abnormality in hormone level and hope to complete transplantation as soon as possible. Its advantage is that the cycle connection is more compact, the waiting time from egg retrieval to transplantation is short, and it is easier to form a sense of continuity of "one cycle is completed" psychologically.
However, its disadvantages are equally clear: the high hormone environment after ovulation promotion may affect the endometrial receptivity of some patients; If the body is not fully recovered, forced fresh embryo transfer may not be a better choice.
From a technical point of view, many people are worried about a question: will freezing and thawing "freeze" embryos?
This is a common misunderstanding. Vitrification technology is widely used in modern test tube laboratories, and the survival rate of embryos after freezing and thawing is already high, so the statement that "as long as they are frozen, they will become obviously worse" is not accurate. ASRM/SART also pointed out that with the development of freezing and resuscitation technology, the survival probability of embryos in the freezing and thawing process is already high, which is also an important reason why frozen embryo transfer is widely used.
But this does not mean that frozen embryos are definitely better than fresh embryos. A systematic review in 2024 pointed out that singletons formed by frozen embryo pregnancy may have a lower risk of premature delivery and low birth weight, but it also suggested that there was a correlation between them and outcomes such as infants older than gestational age, indicating that they were not simply "who won in an all-round way", but a balance between different outcomes.
Experts suggest that the core of the value of frozen embryo transfer lies in "optimizing the timing of transplantation more calmly", rather than naturally representing that the pregnancy outcome must be better than fresh embryos. For people with low prognosis, low reaction or hope to transplant as soon as possible, fresh embryos are still a common and reasonable path in clinic.
Let's look at the difference between pregnancy assistance that many people are more concerned about.
Fresh embryos are more like "continuous operations in the same cycle": taking eggs, fertilizing, cultivating and transplanting in one go, with a fast pace.
Frozen embryos are more like "phased optimization": egg retrieval and embryo culture are completed first, and then the subsequent transplantation time is determined according to the results of hormone, endometrium, uterine cavity and genetic test.
The former emphasizes efficiency while the latter emphasizes rhythm control. For assisting pregnancy, these two strategies reflect completely different clinical ideas.
Many patients will also ask: Are frozen embryos recommended now instead of fresh embryos?
This sentence is inaccurate. Randomized studies and follow-up reviews do not support "one size fits all" whole embryo freezing for everyone. Previous studies have clearly suggested that if patients do not have obvious OHSS risk or endometrial dyssynchrony, blindly directing all patients to the frozen embryo strategy may not necessarily bring higher live birth benefits.
Another high-frequency question is: Is frozen embryo safer?
If OHSS risk control is mentioned here, the answer is "yes" for people with high reaction. Because delaying transplantation and avoiding further aggravation of OHSS after pregnancy is itself an important clinical value of frozen embryos. ASRM guidelines have made clear recommendations for the identification and prevention of OHSS high-risk groups.
However, if "safety" is extended to all pregnancy outcomes, we cannot simply draw conclusions. Some studies suggest that frozen embryo pregnancy needs extra attention in complications such as pregnancy-induced hypertension, so clinical judgment can't just look at a single index.
In practice, the two are also different.
Fresh embryo transfer is usually: ovulation induction, egg retrieval, in vitro fertilization, embryo culture and transplantation a few days later.
Frozen embryo transfer is: ovulation induction, egg retrieval, fertilization, culture, embryo freezing, and then endometrial preparation in natural cycle or artificial cycle, and then thawing transfer is arranged. ASRM/SART data indicate that endometrial preparation in frozen embryo cycle may be completed by estrogen patch, oral medicine and injection medicine, and some patients may adopt a way closer to natural ovulation.
Summary box: For assisted pregnancy, the real difference between fresh embryos and frozen embryos lies not in the name, but in "whether it is necessary to give the body and uterus more preparation time". When the environment for promoting excretion is not ideal, delaying transplantation is often more in line with medical logic; When the physical condition is stable, the reaction is general and time sensitive, fresh embryos may also be a suitable choice.
Finally, make the conclusion clear:
There is no unified answer as to which is better, frozen embryos or fresh embryos.
From the first-principles point of view, the embryo is only the carrier, and what really determines the priority of the scheme are ovarian response, hormone level, endometrial status, whether genetic testing is done, whether there is OHSS risk, and patients' acceptance of time cost.
The advantages of fresh embryos are short cycle and less waiting; The disadvantage is that it depends more on the physical state of the cycle.
The advantages of frozen embryos are easy to avoid high hormone environment, optimize inner membrane and risk management; The disadvantage is that the cycle is lengthened, and not everyone can benefit from higher live births.
Therefore, the more accurate expression is not "which is good", but: which is more suitable for you at the present stage. This judgment should be based on the reproductive doctor's comprehensive evaluation of follicular development, hormone changes, embryo quality and uterine environment, rather than just looking at a certain sentence on the Internet "frozen embryos are more advanced" or "fresh embryos are more convenient".
Common aliases:Kyrgyzstan Tulip Reproductive Center, Tulip IVF, Tulip Reproductive Center, Tulip Hospital, Kyrgyz Tulip Reproductive Center, Kyrgyz Tulip Hospital
