For women. General factors that can affect the ability to ovulate, conceive, or deliver a child successfully include the following:

• Age. Women in their late 30s and older are generally less fertile than women in their early 20s

• Endometriosis

• Chronic diseases (diabetes, lupus, arthritis, hypertension, or asthma)

• Hormonal imbalance

• Environmental factors. Cigarette smoking, alcohol consumption, or exposure to workplace hazards or toxins

• Excessive or very low body fat

• Abnormal Pap smears that have been treated with cryosurgery or cone biopsy

• DES taken by mother during pregnancy

• Sexually transmitted diseases

• Fallopian tube disease

• Multiple miscarriages

For men. Infertility is not just a woman's problem. Following is a list of risk factors related to male infertility:

• History of prostatitis, genital infection, or sexually transmitted diseases

• Exposure to hazards on the job or toxic substances, such as radiation, radioactivity, welding, and many chemicals, including lead, ethylene dibromine, and vinyl chloride.

• Cigarette or marijuana smoke

• Heavy alcohol consumption

• Exposure of the genitals to high temperatures

• Hernia repair

• Undescended testicles

• Prescription drugs for ulcers or psoriasis

• DES taken by mother during pregnancy

• Mumps after puberty