Q.Explain the meaning, causes and nature of intellectual disability.

Prenatal Causes of Disability

Start with the intuition

Think of a baby's development before birth as the most intricate construction project in the universe. Over nine months, a single fertilised cell divides into trillions of specialised cells, forming organs, limbs, a brain, and a nervous system — all in the right places, at the right times, in the right sequence. Any disruption during this process can leave a lasting mark.

A prenatal cause of disability is simply any factor that interferes with that construction before the baby is born — while the child is still in the womb. The disability may be physical (like a missing limb or a heart defect), sensory (blindness or deafness), intellectual (affecting learning and cognition), or a combination.

The precise statement

The three main categories

Prenatal causes fall into three broad buckets. Understanding these helps you see why a particular disability occurred — not just that it occurred.

1. Genetic and chromosomal abnormalities

The blueprint for building a human is written in DNA. Sometimes the blueprint has a mistake — a missing gene, an extra chromosome, or a faulty instruction. Down syndrome (an extra copy of chromosome 21), cystic fibrosis, and muscular dystrophy are examples. These are present from the moment of conception and are not caused by anything the mother does or does not do.

2. Maternal infections and illnesses

A pregnant woman's body is the baby's entire environment. If she contracts certain infections, the pathogen can cross the placenta and damage the developing tissues. Rubella (German measles) in the first trimester can cause deafness, heart defects, and cataracts. Cytomegalovirus, toxoplasmosis, and Zika virus are other well-known examples. Maternal conditions like uncontrolled diabetes or thyroid disorders can also affect fetal development.

3. Environmental and lifestyle factors

Substances the mother is exposed to can act as teratogens — agents that cause birth defects. Alcohol is the most common: fetal alcohol spectrum disorders result from drinking during pregnancy and can cause lifelong intellectual disability, facial abnormalities, and behavioural problems. Other teratogens include certain medications (like thalidomide, a historic tragedy), illicit drugs, radiation, lead, and mercury. Poor maternal nutrition — especially folic acid deficiency — increases the risk of neural tube defects like spina bifida. …