Common birth defects

Researchers have identified over 4000 different birth defects with causes such as genetic problems – a gene missing or one or more genes not working properly, problems with chromosomes such as having an extra chromosome or missing a part of a chromosome. Other causes may include unknown factors or environmental factors to which a pregnant woman is exposed to, for instance rubella or German measles, drugs, alcohol abuse etc.

According to Dr Prakash Vaidya, consultant paediatrician at the Wockhardt Hospitals, Mulund and Jupiter Hospital in Thane, the most common birth defects include physical defects as in having an extra digit in the hand etc, cleft palate or cleft lip. “Some babies are born with ear or eye problems, structural defects like neural tube defects, hypothyroidism and many more. Congenital genetic defects and chromosomal defects such as Down’s syndrome are also common”, he adds.

Of all genetic disorders involving chromosomal problems Down’s syndrome has the highest prevalence. Around 1 in 800 births result in a child with Down’s syndrome in India, writes Dr Harshpal Sachdev and his colleagues at the Department of Paediatrics, All India Institute of Medical Sciences, New Delhi.

Types of birth defects

Structural defects – cleft lip, cleft palate, heart defects such as problems with valves, abnormal limbs such as a club foot, neural tube defects such as spina bifida, defects related to the growth and development of the brain and spinal cord.

Functional defects – These defects often result in developmental disabilities. Problems with the brain or nervous system can give rise to learning disabilities, mental retardation, behavioural disorders, convulsions or movement problems. Autism, Down’s syndrome amongst the birth defects that affect the nervous system.

Sensory defects may cause visual trouble, cataract, and blindness, hearing loss or deafness.

Metabolic disorders can involve a body process or chemical pathway or reaction resulting in hypothyroidism or phenylketonuria (PKU).

Degenerative disorders such as muscular dystrophy can cause health problems that may steadily get worse.

A combination of factors can cause birth defects resulting in both structural and functional problems.

Check list

• Cleft lip or palate mouth or lip do not align right before birth
• Clubfoot – foot and ankle bones do not form right
• Spina bifida – spine does not close
• Anencephaly – brain does not develop
• Neural tube defects – spine does not form properly
• Cerebropalsy – brain and muscle problems occur because of German measles during pregnancy, different blood types (Rh) of mother and baby
• Heart defects – heart does not develop properly, valve defects
• Cystic fibrosis is genetic; makes thick sticky mucus making it hard to breathe and eat
• Down’s syndrome has no cure. The baby shows typical facial features, may have mental retardation and may have heart problems
• Phenylketonuria (PKU) can cause mental retardation. The baby cannot process protein
• Sickle cell anaemia – a disorder of the red blood cells that runs in families
• Tay-Sachs disease – genetic and fatal
• Foetal alcohol syndrome (FAS) can cause mental and physical problems in babies

Advice to mothers

Treatments for birth defects vary according to the disorder. In order to prevent birth defects if you have a history of birth defects, consult your doctor before getting pregnant and get prenatal screening or tests done after you become pregnant to diagnose a defect if there is one. A genetic counselor can brief you about prenatal testing and help you deal with any concerns or fears you might have.

“It is best to avoid unnecessary medications during pregnancy, stop smoking and avoid alcohol during pregnancy. A healthy diet, exercise, rest, getting regular prenatal check-ups, taking iron and folic acid – vitamin B supplements can help you sail through your pregnancy with ease,” avers Mumbai-based obstetrician and gynaecologist Dr Rita Mayekar.

Pic: roli seeger