Several key factors are known to increase the risk of infertility. These factors include:

Age: In women, ovarian reserve and egg quality significantly decline after the age of 35, which also elevates the risk of miscarriage.
Smoking: Tobacco use can damage the cervix and fallopian tubes, and is associated with an increased risk of miscarriage and ectopic pregnancy. It is also believed to accelerate ovarian aging.
Weight Imbalance: Both being significantly overweight and underweight can adversely affect ovulation patterns.
Alcohol Consumption: Excessive alcohol intake is recognized as a factor that can diminish fertility.