生育地圖What is the difference between first, second, and third generation IVF? How to choose?
Commonly referred to as 'first, second, and third generation IVF' correspond to three different techniques: first generation is conventional in vitro fertilization (IVF, where eggs and sperm are placed in the same dish for natural fertilization), second generation is intracytoplasmic sperm injection (ICSI, where a single sperm is directly injected into the egg by an embryologist), and third generation is preimplantation genetic testing (PGT, which screens embryos for chromosomal or genetic abnormalities before transfer). The newer generation is not necessarily more suitable; rather, each corresponds to different causes of infertility, and the choice is made by a reproductive medicine specialist based on the couple's condition. The following is neutral information and does not constitute medical advice.
Taiwan Society for Reproductive Medicine (TSRM) ↗
First, second, and third generation IVF: see the differences in one table
The commonly called three 'generations' correspond to different technical steps, not generational replacements—they can be combined (e.g., second generation with third generation embryo testing). The table below summarizes each technique and common indications.
| Item | First Generation IVF (IVF) | Second Generation IVF (ICSI) | Third Generation IVF (PGT) |
|---|---|---|---|
| Full name | Conventional in vitro fertilization | Intracytoplasmic sperm injection | Preimplantation genetic testing |
| Fertilization / method | Sperm and eggs are placed in the same dish; sperm enter eggs naturally | Embryologist selects a single sperm and injects it directly into the egg | After fertilization, a few cells are taken to analyze chromosomes or genes, then select embryos for transfer |
| Common indications | Female factors (e.g., blocked fallopian tubes, ovulation disorders) with normal sperm parameters | Male factors (low sperm count, poor motility or morphology) or previous poor fertilization | Risk of chromosomal or single-gene disorders, advanced maternal age, recurrent miscarriage, or repeated implantation failure |
The newer generation is not necessarily more suitable; each corresponds to different causes of infertility. Actual choice is made by a reproductive medicine specialist. This is neutral information, not medical advice.
What is the difference between PGT-A, PGT-M, and PGT-SR? What does each test?
Third generation IVF (PGT, preimplantation genetic testing) is divided into several common types based on the target of testing, with different purposes and indications.
| Type | Target | Common indications |
|---|---|---|
| PGT-A | Chromosomal 'number' abnormalities (aneuploidy) | Advanced maternal age, recurrent miscarriage, repeated implantation failure |
| PGT-M | Specific 'single gene' genetic disorders | Couples known to be carriers of single-gene diseases (e.g., thalassemia, spinal muscular atrophy) |
| PGT-SR | Chromosomal 'structural' abnormalities (e.g., balanced translocation, inversion) | One partner carries a chromosomal structural rearrangement |
Whether to perform PGT and which type depends on the physician's assessment based on age, medical history, and genetic risk; not everyone needs it.
This is neutral information, not medical advice.
What is the difference between culturing embryos to day 3 and day 5 (blastocyst)? What does embryo grading mean?
After fertilization, embryos are cultured in the lab. There are two common observation and transfer time points:
- Cleavage stage embryo (day 2–3): about 4–8 cells, not yet clearly differentiated.
- Blastocyst (day 5–6, commonly called blastocyst culture): cells increase and differentiate into the 'inner cell mass' (which develops into the fetus) and 'trophectoderm' (which forms the placenta). Culturing to blastocyst allows natural selection, facilitates PGT sampling (usually from trophectoderm), and supports single embryo transfer.
Embryo grading describes the morphological state of the embryo. Blastocysts are often graded as 'expansion grade (1–6) + inner cell mass (A/B/C) + trophectoderm (A/B/C)', e.g., 4AA; cleavage stage embryos are often graded by cell number and fragmentation. Grading describes the current morphology and is one of the lab's observational indicators.
Grading is a morphological description and does not predict outcomes; embryo culture and transfer strategies are determined by the medical team based on individual circumstances. This is neutral information, not medical advice.
Before IVF, how does the doctor decide between conventional fertilization and ICSI?
Both are in vitro fertilization. The choice between conventional fertilization (first generation) and ICSI (second generation) usually considers several factors:
- Semen analysis results: sperm concentration, motility, and morphology are important indicators of the ability to fertilize naturally.
- Previous fertilization history: if previous cycles showed poor fertilization, the doctor may switch to ICSI.
- Whether PGT is planned: when PGT is performed, ICSI is often used to reduce interference from excess sperm attached to the embryo.
- Number and maturity of retrieved eggs: also considered.
In some cases, labs may use 'split fertilization' (part conventional, part ICSI). About 16–18 hours after fertilization, normal fertilization is confirmed (by observing two pronuclei, 2PN).
In non-severe male factor cases, ICSI is not necessarily more beneficial than conventional IVF; the method is chosen by the physician based on individual assessment. This is neutral information, not medical advice.
FAQ
What is first generation IVF (IVF)? What conditions is it suitable for?
First generation refers to conventional in vitro fertilization, where retrieved eggs and processed sperm are placed in the same dish, allowing sperm to enter eggs naturally, similar to natural fertilization. It is commonly used for female factor infertility, such as blocked or damaged fallopian tubes, ovulation disorders, with normal sperm parameters. Actual suitability is determined by the physician.
What is the difference between second generation IVF (ICSI) and first generation?
Second generation is intracytoplasmic sperm injection (ICSI), where an embryologist selects a single sperm with good morphology and motility under a microscope and injects it directly into the egg. It is mainly used for male factor infertility (low sperm count, poor motility or morphology) or previous poor fertilization. Neutral information: in non-severe male factor cases, ICSI is not necessarily more beneficial than conventional IVF for live birth; the choice is made by the physician based on individual assessment.
What is third generation IVF (PGT)?
Third generation refers to preimplantation genetic testing (PGT), where a few cells are taken from the embryo before transfer to analyze chromosomes or genes, selecting embryos with normal chromosomes or genes for transfer. Common types include PGT-A (screening for chromosomal number abnormalities), PGT-M (testing for single-gene disorders), and PGT-SR (testing for chromosomal structural abnormalities). Suitability and testing type are determined by the physician based on medical history and genetic risk.
Which generation (first, second, or third) is more suitable for me?
There is no superiority among the three; they target different causes of infertility: female factors often use first generation, male factors often use second generation, and for chromosomal or genetic disease risks, the physician may recommend third generation. The actual choice requires evaluation by a reproductive medicine specialist based on medical history, semen analysis, ovarian function, etc. This page provides neutral information.
Is there a 'fourth generation IVF'?
Sometimes 'fourth generation' is used to refer to techniques such as ooplasmic transfer or mitochondrial (spindle) transfer, which are mostly in research or experimental stages and are not approved as routine clinical assisted reproductive procedures in Taiwan. Legal implementation depends on the latest regulations and announcements from the Ministry of Health and Welfare.
Is third generation IVF (PGT) necessary?
Not everyone needs it. PGT is an optional embryo test; physicians typically recommend it in cases of advanced maternal age, recurrent miscarriage, repeated implantation failure, or known chromosomal/single-gene disease risk. Whether to perform it and which type is decided after discussion between the physician and the couple. This page does not constitute medical advice.
Does the choice of generation relate to cost and government subsidies?
The choice of technique depends on medical need, not price. Different techniques and whether PGT is added affect the overall cost; subsidies follow government program regulations. For neutral information on costs and subsidies, please refer to the pages 'How are IVF costs calculated?' and 'How to apply for government IVF subsidies?' on this site.
How do I know which IVF technique is suitable for me?
You need to be evaluated by a reproductive medicine specialist, which typically includes medical history, semen analysis, ovarian function tests (e.g., AMH, ultrasound), etc. Based on the cause of infertility, the doctor decides whether to use conventional fertilization or ICSI, and whether to add PGT. This page provides neutral information and cannot replace individual diagnosis and advice from a physician.
Further References (Official Data Sources)
· This page is a neutral compilation of information, for reference only, not medical advice, and does not constitute any treatment commitment. Actual regulations and treatments should be based on announcements from competent authorities and explanations from qualified physicians.
