LESS COMMON FACTORS AFFECTING FERTILITY
The male tubes. A man’s tubes, the vas deferens, may have developed abnormally (congenital blockage), or they may have become blocked by infection or trauma, or surgery.
The veins. The veins in the scrotum can become swollen, like varicose veins on the leg. This is called a varicocoele, and it can interfere with the temperature maintenance of the scrotum, and the temperature of the testes can become too high. This leads to poor quality sperm, and can impair fertility.
Other male factors. Infection in the system can affect sperm production and quality. Faulty plumbing, which forces the ejaculate (semen) to go backwards instead of forwards, and anatomical defects in the male genitalia are also cited as causes of infertility.
Chromosomes. If a woman or man has a chromosome abnormality it may affect their ability to reproduce. Chromosomes are the bits of genetic material we inherit from the egg and the sperm we developed from, which came from our parents.
Chromosomes determine many things about us, like what sex we are, the colour of our eyes, and other genetically inherited characteristics. Usually women and men have forty-six chromosomes, and two of those determine what sex a person is. The chromosomal pattern for most women is 46 XX, and for men it is 46 XY, the X and Y chromosomes being the sex-determining ones. If the combination of the chromosomes from the egg and the sperm is incorrect at the time of fertilisation the resulting conceptus will have an abnormal chromosome pattern. Many abnormal patterns are not consistent with survival, and the pregnancy may spontaneously miscarry. If the chromosomal mismatch is not life-threatening, a baby may be born and have some degree of abnormality with whatever systems relate to the abnormal chromosomes.
Some women (about one in 2,500 female babies) may have what is known as Turner’s syndrome, because their chromosomal make-up is different. They are definitely women, but they are missing one of the X chromosomes (45 XO). There are typical characteristics, including lack of sexual development at puberty, when the condition usually becomes obvious. Women with Turner’s syndrome have very poorly developed ovaries, and are infertile. Some forms of Turner’s syndrome are incomplete (called ‘mosaic’), and may not be discovered until later in life, after normal sexual development. The ovaries, however, do not tend to work well, and the women are generally infertile.
Men can have chromosomal abnormalities similar to those in women. Men can have Klinefelter’s syndrome (chromosome complement 47 XXY). They have one too many sex chromosomes, and this results in their testes not producing sperm.
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