Congenital abnormality is not only a difficult subject to discuss but it is almost impossible to consider the problem in its correct perspective. It is probably true that every, or nearly every, expectant mother and father is either anxious about, or secretly afraid of, the possibility of their child having some form of congenital abnormality.
It is comparatively easy to talk about the percentage of this and that and indeed percentages of congenital abnormalities are presented later in this chapter, but for those who may either suffer from a congenital abnormality or for the parents of a congenitally abnormal child there is little satisfaction or help to be obtained from a table of statistics and what is meant by normality should be considered before contemplating what is considered abnormal.
Outside the theoretical realms of the Deity the perfect human being does not and cannot possibly exist. There are several reasons for this. Ideals of perfection differ from person to person, making it impossible to create, even in theory, a perfect human who would satisfy everybody’s preconceived criteria and, even if each one of us were to consider creating a model of our own ideal person, either he or she would have to combine within one mind and body so many different and yet powerful attributes that it would be an impossibility.
Even though we cannot achieve perfection we can achieve normality. But is this really true ? When we look at ourselves, our friends or members of our family, we have come to accept our minor imperfections as being part and parcel of a normal person. Some of us have either big ears or little ears, big noses or little noses, big teeth or crooked teeth, or too much hair or too little hair or a crooked toe, a wart, a mole or even perhaps, a small birthmark. No one would suggest that these are really gross imperfections and yet they are congenital abnormalities. Furthermore, the intellect and personality present in a new-born baby are subject to so many external influences and environmental variations that it is small wonder that some of us have bad tempers, fail to pass exams or fail to develop our full potential ability in some particularly valuable artistic or creative attribute.
From a purely medical point of view a congenital abnormality is an abnormality that will, if untreated, adversely affect a person’s normal role in society, but to a mother or father the term congenital abnormality means something much more simple and straight-forward. The child is either mentally and physically normal or it is not. The incidence of congenital abnormality is approximately 4 per cent, which means that 96 out of every 100 babies are normal while 4 in every 100 suffer from some type of congenital abnormality which may require medical or surgical treatment. These abnormalities can be divided roughly into four groups, of which one-quarter are mild, one-quarter moderate, one-quarter severe and one-quarter incompatible with life.
Mild Congenital Abnormalities
These are present in approximately 1 per cent, or 1 in every 100 of all births, and include such minor abnormalities as extra fingers and toes, large birthmarks, skin tags attached to the ear, or hernias at the umbilicus. Some of these require no treatment while others are very easily corrected by minor operations without leaving any permanent defect.
Moderate Congenital Abnormalities
Approximately 1 in every 100 babies suffers from a congenital abnormality of moderate degree, although it is realized that in the eyes of the parent they appear to be very severe. Although they are serious, they can be either totally or partially corrected by medical or surgical treatment to such an extent that a normal life is confidently anticipated. They include congenital dislocation of the hip, club foot (which is usually completely cured if treatment begins in the first few days of life), hare lip and cleft palate (for which surgical correction is now well acknowledged), congenital abnormalities of the heart (for which modem surgery can almost work miracles), and blockage or stoppage in the intestine (which can also be corrected surgically).
Severe Congenital Abnormalities
Approximately 1 per cent of babies suffer from abnormalities of such severity as to influence their lives. These abnormalities cannot be corrected and include mongolism, spasticity, blindness, deafness, absent limbs and congenital lesions of the heart and intestine for which there are no satisfactory surgical solutions.
Congenital Abnormalities incompatible with Life
Severe abnormalities which are usually incompatible with life affect 1 in every 100 babies delivered. These include hydrocephalus, where the head is grossly enlarged by an excess amount of water, anen-cephalus, where the skull is not properly formed, and instances when babies have multiple congenital abnormalities. There is usually little or nothing that can be done to correct such abnormalities. Modern medicine and surgery may achieve minor miracles in saving or prolonging life but it cannot perform the impossible.
It is undoubtedly true that nature has its own defence mechanism and eliminates some grossly abnormal foetuses at a very early stage of their development, which means that a number of abnormal pregnancies are miscarried early in pregnancy. These include the blighted ovum. It is generally accepted that approximately 10 per cent of all human pregnancies are sufficiently abnormal to result in early abortion. Other factors are responsible for the remainder of spontaneous abortions.
Diagnosis of Congenital Abnormality
It is very difficult to diagnose congenital abnormality during pregnancy but it can nevertheless be done if there is any reason to suspect that any abnormality may be present.
A sample of amniotic fluid can be removed from around the baby by amniocentesis at about the 16th week of pregnancy. This test shows the sex of the child and may demonstrate a mongol abnormality. It is performed for a genetic predisposition to mongolism and the diagnosis at this early stage is essential if there is to be a termination of pregnancy. There are several rare diseases that may be diagnosed by such tests. A diagnosis of Rhesus incompatibility is usually made by testing the blood, and the effect on the baby is judged accurately by taking several samples of amniotic fluid later in pregnancy. Similarly, some hospitals can offer screening for spina bifida babies by testing the mother’s blood, suspicious results being confirmed by amniocentesis.
Ultrasound and X-rays are used to establish a diagnosis of hydrocephaly or anencephaly as well as to show the presence of multiple congenital abnormalities.
When a diagnosis has been made of a congenital abnormality incompatible with normal life it is usual for termination of the pregnancy to be considered. The pregnant woman and her husband are told all the facts and these are discussed fully with them. If the pregnancy is to be terminated the woman is admitted to hospital, and premature labour induced.
One particular type of congenital abnormality known as phenylketonuria, if untreated, causes a child to become mentally defective. The disease can be detected by examining the blood of the baby shortly after delivery and can be completely treated. This is a routine test taken on the seventh day after delivery.
Cause of Congenital Abnormality
The cause of most congenital abnormalities is not really known, simply because there are so many factors involved. Many abnormalities are hereditary but the reason why they suddenly affect a particular child is not known, although a greater understanding of the science of genetics will eventually provide the answer. Some abnormalities are transmitted only through the female while others are transmitted solely by the male. Others can result only if a specific genetic abnormality is present in a latent or previously unrecognized form in both parents; the presence of such a latent abnormality in one parent alone will not result in an abnormal child, although the child itself may be capable of transmitting the condition if it should marry a person with a similar genetic abnormality.
Just to make life more difficult and the whole subject more complex, a congenital abnormality of genetic nature may also occur either spontaneously or as an inherited abnormality. One such condition is congenital dislocation of the hip which is known to be hereditary in large areas of Northern Italy where it is fairly common, and which also occurs as an isolated abnormality in this country, not usually associated with a family history or with an increased liability of being transmitted to the next generation.
It is impossible here to deal comprehensively with the whole complicated subject of genetics or with the extensive science of chromosomal abnormalities that are known to cause congenital abnormalities. If necessary, further advice should be sought from the family doctor and perhaps from a specialist in genetic diseases.
Congenital abnormalities occur more frequently in babies of women who are under the age of 16 at the time of delivery and in those who are over 40. It is not known why children of very young mothers suffer from a higher than average incidence of severe congenital abnormality. There is an increased incidence of mongolism in a woman having a baby when she is over 40. If there is any family history, near or far, of a mongoloid child then any woman over 40 years of age should consult her doctor, or a genetic specialist, before starting a pregnancy, especially if it is her first.
Acquired factors, such as drugs or diseases, account for less than one-third of the total number of congenital abnormalities but they are believed to be responsible for some of the more severe types of abnormality.
Virus diseases, such as rubella (German measles), may result in a congenital abnormality. If a woman has German measles during the first 12 weeks of her pregnancy then she has a 10 to 30 per cent risk that her child will be affected. For other virus diseases the risk is very much less.
X-rays. There is no evidence that X-rays taken during pregnancy result in any harm, damage, or congenital abnormality in the baby. However, X-rays of the unborn baby may predispose to the development of leukaemia before the child has reached adulthood, and are certainly damaging to the unborn baby’s genes and chromosomes so that the incidence of congenital abnormality in subsequent generations may be increased. X-rays are thus better avoided during pregnancy unless they are necessary to provide essential information.
Oxygen lack. Deprivation of oxygen during the first 3 months of pregnancy predisposes to congenital abnormality. The two main causes of this—flying in unpressurized aeroplanes and inadequate general anaesthesia—have long since been removed. Passenger aircraft are now pressurized and there is no danger to a pregnant woman from flying in modern aircraft during early pregnancy, providing of course that everything else is normal. She should not, 506 however, fly in unpressurized aircraft above a height of 5,000 ft. or go up mountains higher than 10,000 ft.
General anaesthesia is now so skilled that people receive more oxygen when they are anaesthetized than when they are awake. However, since it involves the administration of drugs which, although harmless, are better avoided during pregnancy purely as a matter of principle, general anaesthesia should be delayed if possible until after the first 3 months. There is no reason why local anaesthesia should not be administered, provided that the correct dose is properly given.
Drugs are better avoided in the first 3 months of pregnancy and the majority of doctors and midwives even refrain from giving simple iron and vitamin tablets until after the end of the third month. Today all drugs are very vigorously tested to see if they exert any adverse influence on pregnancy or cause any congenital abnormality, and most are completely safe. Some drugs, however, are still under suspicion and only those specifically prescribed by a doctor should be taken.
Maternal health before the onset of pregnancy has a great effect on the pregnancy itself, but babies have a habit of surviving quite happily even in the most extraordinary circumstances—women who are suffering from extreme degrees of starvation will give birth to absolutely normal babies of almost normal weight. Maternal disease, however, such as diabetes, abnormalities of the thyroid, abnormalities of the kidney and raised blood pressure do require careful management. Uncontrolled diabetes can cause congenital abnormalities in the baby and, besides making absolutely certain that her diabetes is properly stabilized before she becomes pregnant, a diabetic woman must be meticulous about its management throughout her entire pregnancy. If she does so, she has no reason to worry.
Prevention of Congenital Abnormality
Health. General health should be as good as possible and any tendency towards anaemia should be corrected before the onset of pregnancy.
Infection. Any possible infection should be cured before the onset of pregnancy and every effort should be made to avoid any form of infection or infectious disease during pregnancy.
Drugs. No drugs should be taken other than those prescribed by a doctor.
X-rays should be avoided in pregnancy unless they are necessary for its management or for the control of disease.
Oxygen lack. Avoid travelling in aircraft that are not pressurized, going up mountains or climbing to heights of more than 10,000 ft. in early pregnancy. General anaesthesia does not cause any reduction of oxygen intake but is better avoided if possible.
Maternal disease. If the mother is subject to chronic illness, especially diabetes, it must be carefully and vigorously controlled before and during pregnancy.