11 Key Factors for IVF Success
The latest research in 2025 reveals that age only accounts for 30% of the weight of the key factors in IVF success rate, and laboratory technology and environmental factors are the key to breakthroughs
I.Age and Ovarian Reserve: The Basis but Not the Only Determinant
The critical effect of age
Under 35: 60-75% success rate, <20% aneuploidy rate Above 40: live birth rate plummets to 10-20%, egg aneuploidy rate >80
Disruptive finding: Spanish multicenter study confirms that even with young donor eggs, women ≥40 years of age have a 4.2% annual increase in the risk of implantation failure due to aging of the uterine microenvironment (RR=1.042)
Quantitative indicators of ovarian reserve
Golden combination of AMH and AFC:
AMH <1.1 ng/ml requires immediate IVF initiation, AFC <6 suggests low reserve Women over 39 years of age with AMH >1.2 ng/ml can still achieve a live birth rate of 25-33%.
II.Male factors and semen parameters: the underestimated contribution of the “other half”.
Sperm quality thresholds
Conventional IVF: sperm viability >40%, fertilization rate increased by 30% at concentrations >15×10⁶/ml
Indications for ICSI: single sperm injection should be activated when sperm morphology is <4% normal or DNA fragmentation >25
Hidden effects of age:
Men >40 years old have a 2-fold increased risk of embryo termination when sperm DNA fragmentation rate breaks the warning line
III.Laboratory technology: a revolution in embryo screening and environmental control
AI-enabled embryo selection
Machine learning model analyzes 100+ features such as embryo morphology, division speed, etc., and achieves 92% accuracy rate of implantation prediction, which is 25% higher than the traditional morphological evaluation
Blastocyst Cultivation Advantages and Risks Balance
Blastocyst transfer (Day5) has a 15% higher clinical pregnancy rate than cleavage-stage embryos (Day3), but a 40% elimination rate
Individualized strategy: Day3 transfer is recommended for those with <5 eggs to avoid unavailability of embryos New findings on environmental control Extreme cold + PM2.5: combined exposure increases the risk of clinical pregnancy failure by 7% (RR=1.07), which can be avoided by frozen embryo transfer Laboratory needs to maintain: 37°C constant temperature, 6% CO₂, 95% humidity, temperature difference >0.5°C affects embryo differentiation
IV.Intervening factors: body weight, lifestyle and ovulation program
U-shaped effect of BMI
| BMI range | Change in live birth rate | machine |
|---|---|---|
| ＜19.5 | ↓ 33% (per unit drop) | hormone secretion disorder |
| 18.5-24.9 | reference value | Optimal ovarian response |
| ≥30 | ↓30% | Elevated inflammatory factors and decreased endothelial tolerance |
- Ovulation Program Breakthrough
Dual Trigger Program (GnRH-a+hCG):
Increased ICSI fertilization rate from 74% to 85% in elderly women
However, the cumulative live birth rate did not differ from hCG single trigger (26% vs 30%)
V. New Directions for Precision Prediction and Intervention
- Iteration of success rate prediction models
MLCS machine learning model: integrating 20+ variables such as age, AMH, semen parameters, etc., live birth prediction ROC-AUC reached 0.91, significantly better than the traditional SART model (AUC=0.76)
2、Breakthrough in uterine anti-aging research
Telomere shortening and endometrial angiogenesis abnormality were recognized as the core mechanism of uterine aging, and targeted drugs entered phase I clinical trials
💎 Summary table of key factor optimization strategies
| considerations | Optimization goals | Clinical interventions |
|---|---|---|
| ovarian reserve | AMH≥1.2 ng/ml | Egg freezing recommended for early onset ovarian insufficiency |
| sperm quality | DNA fragmentation < 15% | Smoking cessation + antioxidants (Vitamin C 500mg/day) |
| BMI management | 18.5-24.9 kg/m² | 150 minutes of cardio per week + Mediterranean diet |
| environmental exposure | PM2.5＜35μg/m³ | Avoid extreme cold during transplantation cycle and activate air purifiers |
| embryo selection | Blastocyst transfer is preferred | Combined with AI morphodynamic assessment |
EXPERT CONSENSUS: The cumulative labor and delivery rate (CLBR) for a single ovulation induction cycle is the gold standard for assessing IVF success, covering fresh + frozen embryo transfer outcomes.CLBR can be as high as 65% for women under 35 years of age, and approximately 20-30% for those over 40 years of age.10 The CLBR can be as high as 20% for women under 35 years of age, and approximately 20-30% for those over 40 years of age.
Core Laws of Fertility Preservation:
Fertility planning completed by age 35 – AMH testing 1x per year – Semen analysis synchronized – Environmental toxins proactively avoided
— Johns Hopkins Reproductive Center White Paper on Fertility Preservation 2025
Success rates can be increased by more than 50% by comprehensively modulating the top 10 factors of IVF success outside of age. Technological evolution is reshaping fertility boundaries, but acting early remains the strongest weapon against time.