Congenital anomalies

Dr Lucky Gupta
Congenital anomalies are also known as birth defects, congenital disorders or congenital malformations. Congenital anomalies can be defined as structural or functional anomalies (e.g. metabolic disorders) that occur during intrauterine life and can be identified prenatally, at birth or later in life.
Congenital anomalies exist all over the world. Due to the huge population and high birth rate there is large number of patients with congenital malformations. India is experiencing a gradual but accelerating demographic switch to non-communicable and genetic diseases. This has resulted from achievements in immunizations, success in providing primary health care, developing a sound health infrastructure leading to a lowering of perinatal and infant mortality rates, by control of environmental disorders. Malformations of central nervous system, musculo-skeletal system and gastro intestinal system are the commonest ones observed. These are the leading cause of infant mortality worldwide, and affected children who survive infancy often struggle with lifelong physical and mental disabilities. Although many birth defects cannot be prevented, the probability of some such conditions can be reduced through awareness.
Causes of Malformations
The major causes of congenital malformation are chromosomal abnormalities, mutant genes, multifactorial disorders and teratogenic agents. A good maternal history must be recorded to find out the operation of teratogenic factors. The common ones are listed below, but these are not discussed in greater detail.
Maternal disease
Heavy metals
In order to define the etiology, it is important to determine the time of gestation when the defect is likely to have occurred. The etiology of common malformations like spina bifida, anencephaly, congenital heart disease, talipes equinovarus etc. is considered to be multifactorial. That is, both environmental and genetic factors are involved in their causation. More information on these points is available for neural tube defects. These are the commonest malformations at birth in India. They have an incidence of about 1 in 250 to 285 births.
As majority of Congenital malformations are not associated with any predisposing etiological factors and are not preventable. During the first trimester of pregnancy, all medications and irradiations should be avoided as far as possible. Girls should be given rubella vaccine before they get married. The incidence of chromosomal disorders in infants of elderly mothers is high. These can be reduced by discouraging active reproduction beyond the age of 35 yrs. The incidence of genetic disorders can be brought down by avoiding consanguineous marriages. There is evidence to suggest that administration of high doses of folic acid during periconceptional periods may lower down the incidence of neural tube defects but there is good evidence that it would also prevent heart disease, exomphalos and cleft lip and palate. In fact, it is likely to prevent all malformations occurring in the midline. The folic acid given in the periconceptional period (beginning at least one month before pregnancy and continued for 3 months after pregnancy) can prevent many malformations.
(The author is Paediatric Surgeon and Urologist)