Infertility

Male Contributing Factors

A reproductive health exam with a specialist will take into account common general factors affecting male fertility, including stress, obesity (estrogen production by adipose tissue blocks GnRH release), genetic disorders, cancer, and tobacco, drug, or anabolic steroid use. Specific factors affecting male fertility include undescended testicles, erectile dysfunction, premature ejaculation, excessive heat (increased temperature impede sperm production), blockage in spermatic cord, and viability of sperm.

Average seminal fluid has a neutral pH (approximately 7.2) and contains nutrients for the sperm to use for energy. On average, 100 to 300 million sperm are produced each day. Fertile ejaculate contains adequate volume and concentration of sperm (100 to 400 million sperm) with enough sperm of normal morphology or shape, and the motility or ability to move from the vagina to the fallopian tubes. Problems with morphology or motility are apparent with the occurrence of sperm with pinpointed head, tapered heads, crooked heads, two heads, and coiled or kinked tails.

Primary hypogonadism is defined as testicular failure, and secondary hypogonadism is defined as defective secretion of gonadotropins from the hypothalamus and/or pituitary. These hormones target three specialized cells for reproduction—the spermatogonia in the seminiferous tubules, the Leydig cells in the connecting tissue between the coiled seminiferous tubules, and the Sertoli cells forming the basement member of the seminiferous tubules. They provide the environment necessary for germ cell differentiation and maturation.

Female Contributing Factors

As with male reproductive health, general factors affect female fertility, including age (women in their late 30s are less fertile than those in their 20s), excessive exercise, stress, weight (either loss or gain), chronic diseases (lupus, polycystic ovary syndrome, arthritis, hypertension, asthma, cancer), and tobacco or drug use. Specific factors affecting female fertility [Page 912]include sexually-transmitted disease resulting in tubal blockage, cervical narrowing from infection, cervical fluid inhibiting sperm motility, immune system antibodies attacking sperm, uterine fibroids, and production of viable eggs. Scientists have in the past stated that women are born with all of the eggs they will produce in their lifetime, but new research indicates stem cells may allow women to produce more eggs and extend reproductive ability.

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