Prenatal stage and infancy

Development passes through stages: prenatal, infancy, childhood (early and late), adolescence, adulthood and old age. Each stage is a temporary period with its own features and rate of change, and its own developmental tasks, milestones expected around that age, such as sitting by about six months or speaking a few words by two years. Children reach them at slightly different times.

Prenatal stage (conception to birth, about 40 weeks). The baby develops according to its genes, but the mother's health and surroundings matter a great deal. Teratogens are environmental agents that can harm the unborn baby: drugs, alcohol and tobacco, some infections, radiation and pollution. The mother's age, nutrition and emotional state also matter.

Infancy (birth to about two years):

• Reflexes come first: automatic movements such as rooting (turning towards a touch on the cheek), grasping (gripping a finger), the Moro reflex (flinging out arms at a sudden noise) and the Babinski reflex.
• Then motor skills develop: holding up the head, sitting, crawling, standing and walking. The sequence is the same everywhere, though timing varies.
• Senses are working at birth but sharpen over the first year: newborns already prefer their mother's voice and smell, and vision becomes much clearer by about a year.

Thinking (Piaget's sensorimotor stage). Infants learn about the world through their senses and actions: looking, touching, sucking, grasping. At first, out of sight is out of mind. Gradually, around the second half of the first year, they develop object permanence: knowing that a toy hidden under a cloth still exists, and searching for it.

Attachment. Babies form a close emotional bond with whoever cares for them most, not automatically with the mother; it may be a father, grandparent or other caregiver. Harlow's famous study with infant monkeys showed they clung to a soft cloth 'mother' rather than a wire one that gave milk: contact-comfort, not just feeding, builds attachment. Smiling back, holding and responding to the baby's signals matter.

Erikson described the first year as trust versus mistrust: warm, reliable care teaches the baby that the world is safe and people can be trusted; cold or unpredictable care breeds mistrust.