IVF success rates decline with age mainly due to reduced egg quality and quantity, which affects fertilization, embryo development, and implantation. A typical age-based chart shows that women under 35 have about 45–55% success per cycle, ages 35–40 drop to around 25–40%, and over 40 fall to roughly 10–20% or lower, with further decline after 43. This happens because aging eggs have higher chances of chromosomal abnormalities, leading to lower embryo viability and higher miscarriage risk. Overall, these numbers highlight that earlier fertility planning improves outcomes, while women in later age groups may need advanced options like multiple IVF cycles or donor eggs to increase success chances.