Fortunately 97 per cent of the babies born in the United States are perfectly normal.
The defects found in the other 3 per cent may be caused by:
Abortion Clinic
• hereditary factors
• mutations
• environmental factors
• disease or deficiency while in the womb
• damage at birth
• metabolic disorders.
Heredity
Some abnormalities are carried from generation to generation, often by healthy people (carriers). The difficulties arise when two carriers have children, as they then have a one-in-four chance of having an abnormal child. If two carriers have normal children, they in turn may be carriers.
The most common diseases that are hereditary or have some hereditary factors are spina bifida and Down's syndrome. (The old name for Down's syndrome was mongolism, but this is now outdated.) Other conditions that may be partly hereditary include hare lip, cleft palate and hip joint dislocations. These conditions result from chromosomal abnormalities. Down's syndrome, for example, is caused by the presence of 47 chromosomes, instead of 46, in every cell. The risk of having a Down's syndrome child increases as the mother gets older.
Some inherited conditions are known as sex-linked recessive because they only affect one sex.
These conditions are shown in men much more often than in women; the mother can carry the disease without suffering from it. One example is haemophilia (a condition in which the blood fails to clot), which is caused by a sex-linked gene transmitted by the female. Although it can, extremely rarely, affect women, there is a one-in-two chance of a woman who carries it passing it on to her sons. Muscular dystrophy (a wasting of the muscles) is another example of a serious condition caused by abnormal recessive genes carried by the female and passed on mainly to males. Less serious sex-linked conditions include colour-blindness - about eight per cent of males are colour-blind, which is twenty times the figure for females.
Couples who are planning to have a family, but know that they run the risk of producing a child with an inherited disease or malformation, may seek the advice of a genetic counsellor at a genetic counselling clinic. The counsellor will study their family histories and with the help of tests may be able to assess how likely it is that they will have an affected child. The couple will then have to decide whether they want to take the risk of having a baby that might be handicapped. Genetic counselling can also be given to parents who have had one abnormal child, to give them some idea of the chances of this happening again.
Early tests such as ultrasound done during the first few weeks of pregnancy, either as a routine measure or to women known to be at risk of producing a handicapped child, can detect two to three per cent of abnormalities.
An expectant mother at risk of having a baby with spina bifida or Down's syndrome will be given an amniocentesis, a test in which a small amount of the amniotic fluid is drawn off and examined. This will show whether the abnormal condition is there. If it is, the parents will be offered genetic counselling to help them to decide whether to continue with the pregnancy or to have an abortion.
The UK Abortion Act (1967) allows for the termination of a pregnancy if there is a risk that the child will be born seriously handicapped. Abnormal foetuses are also more likely to be naturally or spontaneously aborted (when the woman is said to suffer a miscarriage) in the early weeks of pregnancy. Six out of ten aborted foetuses are found to have defective chromosomes.
What Are the Chances of Having a Baby With Down Syndrome?
To find out more about your chances of having a Downs Syndrome baby check out the charts and diagrams at http://www.babybirthbasics.com/testing-for-downs-syndrome-and-other-disorders.