Secondary infertility refers to a situation where a couple has successfully given birth to a child, but still cannot conceive after about a year of natural pregnancy. Causes of secondary infertility may include women over 35 years old, reduced sperm count in men, polycystic ovary syndrome in women, being overweight, etc. Treatment methods include medication, artificial insemination, in vitro fertilization surgery, etc. IVF assisted reproductive technology in the United States is mature and has a high success rate, making it an effective choice for the treatment of secondary infertility.