Three stages of development: germinal- begins at fertilization, when sperm unites with ovum (egg, egg is called a zygote- divides. Increases likelihood of miscarriage, premature birth, abnormal fetal heartbeat, underweight baby. Culture and maturation: many aspects of development affection by cultural customs of how their parents hold, touch, feed and talk to them, canada and western, babies expected to sleep eight hours by four/five months. Neurological maturity: mayan, rural italy, africa, india, urban japanese- nurse every four hours first few years. Sleeping with baby forges a bond: milestone for crawling used to be six-eight months, now some don"t crawl at all. Used to sleep on stomach, easy to push up and crawl. Since 1990"s, babies sleep on back so don"t suffocate- crawling harder. Avoidant- don"t care when mother leaves, treated same as stranger. First few months babies cry and coo; they respond to emotions and rhythms in voices.