Infertility Causes

 

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Infertility is defined as lack of conception after twelve months of normal sexual activity without contraception. Fifteen percent of couples experience difficulty conceiving. With advances in treatment of infertility, publicity about IVF, and the near disappearance of adoption as an alternative, couples frequently seek help from their doctor. The aim of this chapter is to discuss the types of problems these people have, how the doctor can help them, and what resources are available in the Hunter. A basic understanding of the causes of infertility is necessary to efficiently initiate investigation of the infertile couple.



Causes of Infertility
Ovulation Disorders (approx. 30%)
Lack of, or infrequent ovulation is becoming more common as obesity becomes more prevalent in our society. Anovulation is suggested by infrequent or absent menses leading to oligomenorrhoea or amenorrhoea. Women with regular menstrual cycles (40 days or less in length) are almost always ovulatory.



Causes include:
Polycystic ovary syndrome
Hyperprolactinaemia
Hypothalamic dysfunction (e.g. stress, weight loss, extreme exercise)
Ovarian failure (premature menopause)

Anatomic Problems
a) Tubal disease (5-10%)
Sexual transmission of such organisms as chlamydia and gonorrhoea can cause pelvic inflammatory disease (PID) which can cause scarring and blockage of the fallopian tubes. Whilst the prevalence of Chlamydia in the Hunter is quite high, rates of PID and hence tubal damage have fallen over the last 10 years reflecting better detection and treatment. Tubal damage can also arise following surgery, appendicitis, post-abortion pelvic infections and accompanying severe endometriosis.
Tubes may be totally or partially blocked and adhesions may affect their mobility.


b) Uterine (1-5%)
Intrauterine lesions can interfere with implantation. Ashermann’s syndrome can occur after surgery or miscarriage- the adhesions within the endometrial cavity severely limit the occurrence of pregnancy. Submucuos fibroids, large intramural fibroids that distort the endometrium and intrauterine polyps can all reduce the chance of pregnancy occurring. Uterine abnormalities do not usually cause infertility but may increase the risk of miscarriage.


c) Cervix
Cervical surgery (e.g. cone biopsy, diathermy) may lead to cervical stenosis or reduced cervical mucous - which can, in turn, decrease fertility.


d) Endometriosis (10-15%)
Endometriosis reduces fecundity possibly by releasing chemical mediators within the pelvis that interfere with tubal and ovarian function. Severe endometriosis where there is anatomic distortion within the pelvis reduces the likelihood of pregnancy even further.



Male Factor (30-35%)
Problems with sperm production are a major contributor to infertility. Fertility is reduced when there is a reduction in sperm number and/or motility and/or quality. A history of an undescended testicle, mumps oorchitis, cancer treatments and certain medications all increase the likelihood of sperm production problems.
Retrograde ejaculation is a rare cause of male infertility. It can arise after surgery on the bladder neck or due to complications of conditions such as diabetes.



Other Causes
Immunologic causes of infertility are occasionally sought. One or both partners may have anti-sperm antibodies in serum or genital secretions.



Sexual issues
Problems with erectile function, ejaculation or vaginismus may sometimes lead to infertility treatment.

Unexplained Infertility (20-25%)
In a significant proportion of couples no cause can be found for their delay in falling pregnant. Without active treatment 20% per year will eventually conceive if the female partner is <35 and they have been trying for less than 5 years total. Many will eventually require IVF.
As you can see from the above the percentages do not add up as many couples will have multiple infertility factors contributing to their delay in falling pregnant. The more factors contributing the less the likelihood of a spontaneous pregnancy occurring.