Fertility problems have many causes that involve either the woman's, the man's, or both partners' reproductive systems. Some causes include:
- Problems with the man's reproductive system.
- Problems with the woman's fallopian tubes.
- Problems with the woman's uterus and/or cervix.
- Problems with ovulation.
Rates of infertility and miscarriage increase with age. A woman's fertility peaks in her late 20s. It gradually begins to decline in her early 30s. A more pronounced drop in fertility and increase in miscarriage risk begins around her mid-30s. This is primarily due to the aging egg supply. Male fertility also decreases with age. But it is a more gradual decline than in women.