Development Irregularities during Pre-natal Period

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Developmental Irregularities during Pre-Natal Period

Introduction:

Causes of Developmental Irregularities

Hereditary Factor

Mendelian Inheritance Patterns:

Dominant Inheritance of Defects:

Recessive

Incomplete

Sex-linked

Chromosomal Abnormalities:

Numeric Chromosomal Abnormalities

Structural Chromosomal Abnormalities

Environmental Factor:

Maternal Nutrition:

Maternal Drug use:

Maternal Illness:

Prevention of developmental Irregularities:

Developmental Irregularities during Pre-Natal Period

Introduction:

The pre-natal period of development covers the time from conception to birth and is sometimes described in terms of trimesters (first, second and third) or of three stages (germinal embryonic, and foetal).

Developmental irregularities are distortion to the normal pattern of development of different physical features.

Causes of Developmental Irregularities:

The major causes of Development irregularities are:

Hereditary factor:

Each of us has genes that are inherited from our parents. The genes occur in pairs along threadlike bodies called chromosomes which are located in the nucleus of each cell in the body. Inherited diseases result primarily from genetic mutations or genetic imbalance passed on from parent to child at conceptions. These include:

Mendelian inheritance patterns:

The simplest patterns of birth defects inheritance are called mendelian. These abnormalities can be transmitted by way of dominant, recessive, incomplete or sex-linked inheritance of defects.

Dominant Inheritance of Defects:

A child inherits two copies of each gene, one from the mother and one from the father. If a defective gene is dominant, a child who inherits even one copy of it will have the defect. This is because the defective copy “dominates” the normal copy inherited from the other parent.

Recessive Inheritance of Defects:

In the case, where the defective gene is recessive, the child would have to inherit two defective copies one from the mother and one from the father in order to have the defect. Examples are Sickle cell anaemia, cystic fibrosis and tay-sachs disease.

Incomplete Inheritance of Defects:

This is pattern of inheritance in which a child receives two different alleles, resulting in partial expression of a trait. For example, people with only one sickle-cell allele and one normal allele do not have sickle- cell anaemia but do show some manifestations of the conditions.

Sex- Linked Inheritance of defects:

Sex-linked recessive traits are carried on one of X Chromosomes of an unaffected mother. The mother is a carrier; she does not have the disorder but can pass on the gene to her children. Sex-linked disorder almost always appears only in male children; in females, a normal dominant gene on the chromosome from the father generally overrides the defective gene on the chromosome from the mother. Boys are more vulnerable to these disorders because there is no opposite dominant gene on the shorter chromosome from the father to override a defect on the chromosome from the mother.

Chromosomal abnormalities:

The chromosomal abnormalities are caused by errors in the number or structure of chromosome.

Chromosomal abnormalities due to chromosomal number (Numeric C.A):-

Egg and sperm cell each contain 23 chromosomes. When they combine, they form a fertilized egg with 46 chromosomes. But sometimes something goes wrong before fertilization. An egg or sperm cell may divide incorrectly, resulting in an egg or sperm cell with too many or too few chromosomes.

When this cell with the wrong number of chromosomes combine with a normal egg or sperm cell, the resulting embryo has a chromosomal abnormality.

 

Structural Chromosomal abnormalities:

The errors before fertilization can alter the structure of one or more chromosomes. The number of chromosomes remains 46 but small pieces of a chromosome may be deleted, duplicated, inverted misplaced or exchanged with part of another chromosome.

Example includes cri-du-chat syndrome, prader-willi syndrome, pallister killian syndrome and robertsonian translocation.

Environmental Factor:

Although the foetus develops in the protective buffer of the womb, events in the external environment can affect it indirectly through the mother. Because the developing organism and its mother are linked through the placenta, a mother’s eating habits, drug use, and physical health, among other things can affect prenatal development.

Maternal Nutrition:

The developing foetus needs a variety of essential nutrients. Thus, it’s not surprising that severe, maternal malnutrition increases the risk of birth complication and neurological defects for the new born. Recent research suggests that prenatal malnutrition may have negative effects decades after a child’s birth. For example, prenatal malnutrition has been linked to vulnerability to schizophrenia and other psychiatric disorders in adolescent and adulthood. Also, low birth weight is associated with an increased risk of heart diseases and diabetes in middle adulthood.

Maternal Drug Use:

A major source of concern about foetal and infant well-being is the mother’s consumption of drugs. Unfortunately most drugs consumed by a pregnant woman can pass through the membranes of the placenta.

Virtually all recreational drugs can be harmful. Babies of heroin users are born addicted to narcotics and have an increased risk of early death due to prematurity birth defects, respiratory difficulties. Prenatal exposure to cocaine is associated with increased risk of birth compilations and a variety of cognitive deficits that are apparent in childhood. Even legitimate medical drugs can cause problems.

Alcohol consumption during pregnancy also carries risks. Foetal alcohol syndrome is a collection of congenital (inborn) problems associated with excessive alcohol use during pregnancy. Typical problems include microcephaly (a small head), heart defects irritability, hyperactivity, delayed mental and motor development. It is also one of the leading causes of mental retardation, depression, suicide and criminal behaviour in adulthood.

Pregnant women who smoke have an increased risk of miscarriage, still birth, prematurity and other birth complications. It many also cause slower than — cognitive development and attention deficit disorder.

Maternal illness:

The foetus is largely defenceless against infections because its immune system matures relatively late in prenatal period. The placenta screens out quite a number of infections agents, but not all. Thus, many maternal illnesses can interfere with prenatal development. Diseases such as rubella, syphilis, cholera, smallpox, mumps and even severe cases of the flue can be hazard zone to the foetus. The nature of any damage depends, in part, on when the mother contracts the illness.

Genital herpes and acquired immune deficiency syndrome (AIDS) are two very deadly diseases that pregnant women can also transmit to their offspring’s.

Prevention of Developmental Irregularities:

No one can guarantee that a body will be born perfect and healthy. However, there are ways to minimize the likelihood of having a child with birth defects. Some of the most important ways involve lifestyle.

Pregnant women should not smoke or drink alcoholic beverages, nor should they use drugs of any kind unless prescribed by a doctor.

Casein vitamin, if taken in proper amounts by the mother to be can help prevent some birth effects. For examples, folate (folic acid) taken during pregnancy can help prevent certain defects of the spinal column and central nervous system, including spina bifida.

Vaccination well before pregnancy can prevent birth defects that might occur if the mother were to develop German measles while pregnant.

Couples should use genetic counselling before planning to have a child if the mother father or relatives have heredity abnormalities.

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