Causes And Risk Factors for Infertility

30 - 40% of all infertility - "male" factor


1. Hormonal problem:
o Quite rare & represent only 1% of all male infertility disorders
o Pituitary tumour & other conditions where the pituitary gland is affected

2. Sperm production problem:
o Sertoli cell-only syndrome
o Maturation arrest à precursor cells are unable to complete their development to sperm in the testis.
o Hypospermatogenesis
o Cryptochisism – Undescended testis
o Genetic causes – Klinefelter’s Syndrome, Down’s Syndrome, etc
o Orchitis – Testes infection, can be viral (Mumps orchitis) or bacterial (epididymo-orchitis)
o Heat:
– Temp: 1-1.5 °c < than body temp (achieved by pampiniform plexus)
– Fever, excessive external heat eg: hot spa, underwear style (tight or loose? Still in reaserch)
o Anti-Sperm antibodies – damaging effect on sperm
o Torsion of testis – blood vessels that supply the testis become twisted
o Varicocele - varicose condition of spermatic cord veins, abnormal valves & dilatation, ¯ sperm count , ‘bag of worms’
o Drugs – anti-cancer drugs, chemicals: pesticides, etc
o Radiation damage – in radiation therapy

3. Sperm blockage:
o Congenital absence of vas deferens – common in Cystic Fibrosis
o Congenital absence of seminal vesicle - ­ acidity of semen
o Infection – eg: gonorrhoea, chlamydia, cause inflammation of reproductive ducts
o Obstruction in region of prostate – infection, ‘cyst’ in prostate gland (congenital)
o Vasectomy

4. Ejaculatory problem:
o Damage to nerve ( pudendal n.) – caused by spinal cord injury, diabetes (neuropathy) & surgery - erectile dysfunction
o Surgery to nerves in pelvis & prostate surgery – may cause damage to sphincter muscle of bladder, lead to retrograde ejaculation
o Timing of intercourse – ref to ovarian & menstrual cycle of female
o Medication – anti hypertensive & anti depression drugs

5. Others:
o Smoking
o Stress
o Excessive alcohol
o Idiopathic – 15%
o 2° causes: Diabetes, obesity, sicke cell disease, chronic renal failure, liver disease, usage of lubricants

· 40 - 50% of infertility - "female" factor

1. Ovulation causes
a. Abnormalities of the thyroid gland
Hypothyroidism leads to increased prolactin release, leading to galactorrhoea. The high prolactin level may prevent normal ovulation, causing decreased fertility, sometimes with irregular or absent menses.
Hyperthyroidism patients have variable menstrual patterns
b. Excessive male hormone (androgens)
Excess androgens in the woman may lead to the formation of male secondary sex characteristics and the suppression of LH and FSH production by the pituitary gland. Elevated levels of androgens may be found in women with polycystic ovaries, or with a tumor in the pituitary gland, adrenal gland, or ovary.
c. Physical stress, psychological stress and extreme lifestyle changes
Stress in women disrupts the hormonal communication between the brain, the pituitary, and the ovary, interfering with both the maturation of an egg and the ovulation process.
d. Poor egg quality
Eggs that become damaged or develop chromosomal abnormalities cannot sustain a pregnancy. This problem is usually age-related -- egg quality declines significantly in the late 30s and early 40s.

2. Cervical causes
This involves inability of the sperm to pass through the mouth of the uterus due to damage of the cervix. Causes include the following:
a. Inadequate or inhospitable cervical mucous
Destroys partner’s sperm
b. Cervical narrowing or "stenosis"
Impedes the passage of semen into the uterus
c. Infections of the cervix
Commonly due to sexually transmitted diseases
d. Immunological infertility
Immune attack of sperm or "sperm allergy" is sometimes diagnosed when the woman's immune system produces "anti-sperm antibodies" that attack her partner's sperm.

3. Pelvic causes
These include any disruption of the normal pelvic anatomy:
a. Scar tissue or "adhesions"
Usually caused by surgery or infection. Pelvic adhesions are actually scar tissue that forms between two or more internal organs. Infertility can occur when the adhesions attach to the ovaries or fallopian tubes.
b. Endometriosis
Endometrial tissue (the uterine lining that sheds with each monthly period) grows outside the uterus
c. Blocked, scarred, or distorted fallopian tubes
Pelvic inflammatory disease (PID) - an infection of the reproductive tract that usually is caused by a sexually transmitted disease but can also stem from a miscarriage, abortion, childbirth or an intrauterine device (IUD).
d. Benign tumors (fibroids) of the uterus
Can interfere with embryo implantation or fetal growth. At least 40 percent of women have these benign uterine tumors, or myomas.
e. Poly cystic ovarian syndrome
Patients whose ovaries contain many small cysts have hormone imbalances and do not ovulate regularly.

4. Uterine causes

a. Thin or abnormal uterine lining
Implantation cannot occur
b. Anatomic problems
Polyps, uterine fibroids, abnormal shape of the uterus, septum or "dividing wall" within the uterus
c. Diethylstilbestrol (DES)
A synthetic oestrogen was given to some women who were at risk for miscarriage during the 1950s and 1960s. Women and men whose mothers took DES while pregnant with them are at high risk for certain reproductive tract cancers and menstrual irregularities. Many DES daughters have an abnormally shaped uterus that can lead to repeated miscarriages. DES sons are prone to cysts in their reproductive tract, undescended testicles and other fertility problems.



· Remaining 10 -30% of infertility - contributing factors from both partners/ or idiopathic

*Estimated that 10 - 20% of couples will be unable to conceive after 1 year of trying to become pregnant.
*Important that pregnancy be attempted for at least 1 year.
- Chance for pregnancy occurring in healthy couples who are both under the age of 30 and having intercourse regularly is only 25 - 30% per month. A woman's peak fertility occurs in her early 20s.
- As a woman ages beyond 35 (and particularly after age 40), the likelihood of getting pregnant drops to less than 10% per month.


Risk factors for infertility:

Multiple sexual partners (increases risk for sexually transmitted diseases)
Sexually transmitted diseases
History of PID (pelvic inflammatory disease)
History of orchitis (Testis infection) or epididymitis in men
Mumps (men)
Varicocele (men)
A past medical history that includes DES exposure (men or women)
Eating disorders (women)
Anovulatory menstrual cycles
Endometriosis
Defects of the uterus (myomas) or cervical obstruction
Long-term (chronic) disease such as diabetes

Source:
Medline - http://www.nlm.nih.gov/medlineplus/ency/article/001191.htm,

advanced infertility institute web site – http://www.fertilitydocs.com/causesof.html

And health A to Z website – http://www.healthatoz.com

Contributed by John Lee