Infertility can result from lack of ovulation, poor quality oocytes, blocked oviducts (Fallopian tubes), impotence in the man, inadequate sperm numbers, poor quality sperm, or a poor interaction between the sperm and the cervical mucus. The numbers and quality of oocytes and sperm decrease significantly with increasing age, resulting in decreased fertilization rates, embryo development, implantation rates, and pregnancy rates. In addition, it is increasingly apparent that the numbers and quality of oocytes and sperm can be affected by lifestyle, notably by smoking, alcohol, obesity, caffeine, and stress. These lifestyle factors can mimic andexacerbate the effects of aging on fertility.