As many as one in six couples of childbearing age may be infertile today in the United States.
About one-third of these cases are due to the woman’s fertility, and one-third is due to the man’s infertility. The other third of infertility cases are attributed either to combined factors for a couple, or to unknown causes.
One cause of male infertility is low sperm count or quality. Engorged veins in the testes can increase blood flow and heat. This affects the sperm amount and shape.
Male infertility also stems from problems with sperm delivery. This can be due to premature ejaculation or semen entering the bladder instead of through the penis.
Genetic diseases, structural problems in the testicle, or damage or injury to male reproductive organs are other causes. Past drug treatment, radiation or surgery and diabetes may also result in male infertility.
When it comes to female infertility, the American Society for Reproductive Medicine reports that abnormal or irregular ovulation accounts for nearly 25 percent of it.
Other factors include fallopian tube blockage or damage. This typically results from an inflamed fallopian tube. An inflamed fallopian tube can be caused by pelvic inflammatory disease (usually from a sexually transmitted disease), endometriosis or adhesions.
Endometriosis alone can affect how the ovaries, uterus and fallopian tubes function.
Problems with the cervical opening or mucus, or abnormalities in the uterine shape or cavity, can lead to female infertility.
Some women experience primary ovarian insufficiency, which is basically early menopause. With POI, a woman’s ovaries cease working and menstruation stops before they reach 40 years of age.
Other factors linked with female infertility include polycystic ovary syndrome, ectopic pregnancy, and having more than one miscarriage. Medical conditions such as diabetes, epilepsy, and bowel and thyroid diseases can result in female infertility.
Certain cancers often severely weaken a woman’s fertility. And cancer treatment — chemotherapy and radiation — may also affect her fertility.
Age plays a part in infertility.
Female fertility begins to wane at around 27 years of age. That’s because of the aging and depletion of her eggs. And men over 35 are two times as likely to be infertile as those under 25 years of age.
Weight is yet another factor in infertility. Twelve percent of female infertility cases result from weighing too little or too much. It hits men as well — obesity affects sperm production.
Cigarette smoking is another equal opportunity offender. Forbes.com said smoking can cause more rapid deterioration of eggs and significantly lower sperm count.
Certain medications can affect both sexes. Antidepressants have been shown to cause irregular menstrual cycles. Other medications have been found to be potentially toxic to sperm.