First and foremost: there is no such thing as a 100% success rate in fertility and IVF treatments. If you hear it, it's most likely just marketing.
The success rates reported by a clinic typically indicate the number of pregnancies as a proportion of the total number of embryo-transfers done in a year.
But they usually don’t distinguish between treatments using one's own eggs/sperm and treatments using donated eggs/sperm/embryos, or by patient characteristics: therefore, these percentages may not be relevant to your specific circumstance. So, ask them about the success rates they had with similar cases to yours: type of treatment, age range, any pre-existing conditions.
When doctors assess your case and make treatment recommendations, they might mention the expected success rate of each option. Make sure to clarify whether they mean per embryo-transfer, per cycle (until all embryos resulting from one stimulation cycles are transferred), or if they are considering multiple stimulation cycles. This will give you a better idea on what to expect.
Consider this: statistically, a healthy young couple has around a 70% probability of natural conception with each cycle. If the percentage you're given is close to this figure, you may feel positive about your chances.
