Infertility in Men - Introduction

Introduction

Infertility is the failure of a couple to become pregnant after one year of regular, unprotected intercourse. About a third of infertility problems are due to female infertility, and another third are due to male infertility. In the remaining cases, infertility affects both partners or the cause is unclear. [For information about female infertility, see In-Depth Report #22: Infertility in women.]

The Male Reproductive System

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Male fertility depends on the proper function of a complex system of organs and hormones:

• The process begins in the area of the brain called the hypothalamus-pituitary axis, a system of glands, hormones, and chemical messengers called neurotransmitters, all of which are critical for reproduction.
• The first step in fertility is the production of gonadotropin-releasing hormone (GnRH) in the hypothalamus, which prompts the pituitary gland to manufacture follicle-stimulating hormone (FSH) and luteinizing hormone (LH).
• FSH maintains sperm production, and LH stimulates the production of the male hormone testosterone.
• Both sperm and testosterone production occurs in the two testicles, or testes, which are contained in the scrotal sac (the scrotum). (This sac develops on the outside of the body because normal body temperature is too high to allow sperm production.)