- environmental agents that cause deviations in normal development that can lead to serious abnormalities or death. Common teratogens include drugs, infections, radiations, and pollution. Intake of drugs (marijuana, heroin, cocaine, etc.), alcohol, tobacco, etc. by women during pregnancy may have harmful effects on the foetus and increase the frequency of congenital abnormalities.
Radiations (such as X-rays), and certain chemicals near industrial areas can cause permanent change in the genes. Environmental pollutants and toxic wastes like carbon monoxide, mercury and lead are also sources of danger to the unborn child. I NFANCY The brain develops at an amazing rate before and after birth. You have already read in Chapter about the parts of the brain and the important role played by cerebrum in human functions, such as language, perception, and intelligence.
Just before birth the newborns have most but not all brain cells. The neural connections among these cells develop at a rapid rate. The newborn is not as helpless as you might think. The activities needed to sustain life functions are present in the newborn — it breathes, sucks, swallows, and discharges the bodily wastes.
The newborns in their first week of life are able to indicate what direction a sound is coming from, can distinguish their mother’s voice from the voices of other women, and can imitate simple gestures like tongue protrusion and mouth opening. Motor Development : The newborn’s movements are governed by reflexes — which are automatic, built-in responses to stimuli. They are genetically-carried survival mechanisms, and are the building blocks for subsequent motor development. Before the newborns have had the opportunity to learn, reflexes act as adaptive mechanisms.
Some reflexes present in the newborn — coughing, blinking, and yawning persist throughout their lives. Others disappear as the brain functions mature and voluntary control over behaviour starts developing (see Table . ). As the brain is developing, physical development also progresses.
As the infant grows, the muscles and nervous system mature which lead to the development of finer skills. Basic physical (motor) skills include grasping and reaching for objects, sitting, crawling, walking and running. The sequence