1. Failure to conceive within one year of unprotected intercourse is clinically defined as infertility May involve one or both partners Men and women involved ~ equally 10 - 15% of couples in US have fertility problems So far, we have discussed sexual anatomy and physiology, sexual response, fertilization, and early development with the assumption that everything works correctly. That is often not the case. Overall, with frequent unprotected sexual intercourse: 50% of couples will conceive within three months 70% of couples will conceive within six months

2. Insufficient number of sperm produced Damage to testes Insufficient stimulation by pituitary Infection or inflammation of testes Stress Obesity Increased temperature of testes Damage to nerve or blood supply to testes (most common cause is varicocele) Some drugs used in treating tumors or infections Aging No sperm produced Defects in testes Undescended testes (cryptorchidism) Pituitary fails to stimulate spermatogenesis Infection or inflammation destroys seminiferous tubules Disorders of sperm production:

3. Blockage of vas deferens, ejaculatory duct, or urethra Usually caused by infection / inflammation Scarring from trauma Birth defects Abnormal function of epididymis Usually due to hormonal disorders Abnormal function of prostate or seminal vesicles Infection / inflammation Damage to their nerves or blood supplies Some hormonal disorders Tumors Some drugs used in treating tumors or infections Aging Disorders of male reproductive tract:

4. Disorders of erection Inability to get or keep erection, or erection too soft (erectile dysfunction or impotence) : Stress / psychological issues Damage to nerves or blood vessels supplying penis Damage to erectile bodies Various drugs used to treat hypertension, high cholesterol, heart disease, kidney disease, liver disease, and others Smoking, alcohol Steroid abuse Poor nutrition

5. Disorders of erection Abnormally persistent erections (Priapism) Damage to nerves or blood vessels Trauma to erectile bodies preventing blood from flowing out Inability to get or keep erection, or erection too soft (erectile dysfunction or impotence) : Stress / psychological issues Damage to nerves or blood vessels supplying penis Damage to erectile bodies Various drugs used to treat hypertension, high cholesterol, heart disease, kidney disease, liver disease, and others Smoking, alcohol Steroid abuse Poor nutrition

6. Insufficient volume of semen Usually secondary to disorders of prostate or seminal vesicles Orgasm without ejaculation: Blockage of ejaculatory duct and/or urethra Prostate and seminal vesicles unable to form semen Disorders of ejaculation Premature ejaculation (before or very early in intercourse) Psychological stress Overstimulation

7. Treatment for male infertility typically involves: Decreasing physiological and psychological stress Lowering temperature of testes to increase sperm production Limiting intercourse to increase number of sperm / ejaculation Stopping tobacco, alcohol, or drug use Correcting nutritional issues Antibiotic treatment of infections Surgical correction of varicocele or blockages Hormone supplementation Erectile dysfunction drugs

8. Similar problems seen in women: Disorders of ovulation: No oocytes produced or oocytes produced at irregular intervals Defects in ovaries Damaged blood supply to ovaries Pituitary fails to stimulate oogenesis Stress Obesity Strenuous exercise Excessive weight loss Some drugs used in treating tumors or infections Estrogen and/or progesterone Aging

9. Blockage of Fallopian tube Usually caused by infection / inflammation Scarring from trauma or ectopic pregnancies Birth defects Fallopian tube unable to transport sperm and/or preembryo Usually secondary to insufficient estrogen and/or progesterone from ovaries Poor nutrition Disorders of female reproductive tract:

10. Uterus will not support implantation and embryo Infection or inflammation Insufficient estrogen and/or progesterone from ovaries Tumors Vaginal constriction or inadequate lubrication Failure of arousal Insuffient estrogen and/or progesterone x (Disorders of female reproductive tract) Endometriosis Usually associated with hormonal disorders Cervical scarring Usually caused by infection

11. Treatment for female infertility typically involves: Decreasing physiological and psychological stress Stopping tobacco, alcohol, or drug use Correcting nutritional issues Antibiotic treatment of infections Surgical correction of endometriosis or blockages Hormone supplementation

12. Treatment for infertility: In many cases where other treatments do not work, a couple will use in-vitro fertilization and embryo transfer. May involve sperm and eggs of both parents, or May involve donated sperm or eggs.