Fertility is the natural capacity to conceive and produce offspring. It depends on a complex interplay of hormonal, reproductive, and overall health factors in both partners. For people trying to conceive, fertility is often discussed in terms of infertility, defined as the inability to become pregnant or achieve a successful pregnancy after one year of unprotected intercourse (or six months for people age 35 and older). Infertility affects approximately 15% of reproductive-age couples and is not limited to women. Male factor infertility accounts for about 30–40% of cases.
Male Fertility
Male fertility depends on the production, motility, and morphology of sperm. Spermatozoa cells are specialized male reproductive cells produced in the testes that carry genetic material and are capable of fertilizing an egg. Healthy sperm have specific characteristics:
- Adequate count (at least 15 million per milliliter of semen)
- Good motility (ability to swim toward an egg)
- Normal morphology (shape and structure)
Male fertility issues can result from problems at any stage of sperm production, transport, or function. Common conditions include low sperm count (oligospermia), poor sperm motility (asthenospermia), abnormal sperm shape (teratospermia), or complete absence of sperm (azoospermia).
Female Fertility
Female fertility depends on regular ovulation, patent fallopian tubes, and a uterine environment conducive to implantation. Each menstrual cycle, the ovaries release a mature egg during ovulation, which travels down the fallopian tube, where it may be fertilized by sperm. The fertilized egg then implants in the uterus and develops into a pregnancy.
Female fertility issues can result from problems with ovulation (polycystic ovary syndrome, irregular cycles), tubal blockage or damage (from endometriosis, infection, or surgery), uterine abnormalities, or hormonal imbalances. Age is also a significant factor. Fertility declines gradually starting in the 30s and sharply after age 35 due to declining egg quantity and quality.