This article discusses infertility issues for both men and women. For men, infertility can be caused by low sperm count, poor sperm motility, or abnormal sperm structure, with no known cause in many cases. For women, infertility can be due to ovulation problems, cervical issues, uterine cysts or fibroids, or endometriosis blocking fallopian tube function. Even after testing, 10% of couples remain infertile with no known reason. Fertility treatment or IVF may help couples have children when naturally conceiving is not possible.