MAJOR DEVELOPMENTAL PERIODS IN HUMAN BEINGS

The major developmental periods in human beings are:

• The pre-natal period; before birth
• The post-natal period; after birth

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Today's focus would be on the prenatal period

The pre-natal period: This is the period before the birth of the child i.e. when the child is in the mother’s womb. This conception period lasted for 280 days i.e. nine calendar months. Fertilization takes place when the sperm penetrates the wall of the ovum cell. The fusion of the male and female gametes forms the zygote. The zygote undergoes three major developmental during the 280 days which is known as pregnancy period. (Komolafe, Ogunjimi &Adeniyi,2005)

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The stages of pre-natal development are as follows:
- The zygotic period (the Germinal Period)

The zygotic period extends from fertilization to the end of the second week. The period is characterizes by growth of the zygote with an initial linkage between the zygote and the support system of the mother. This is the period of rapid growth as a result of increase in cells. The zygote is in the uterine wall after fertilization.

- Embryonic Period

The embryonic period lasts from fertilzation to the end of the second week to the end of the eight weeks. The period is characterized by rapid growth as the developing organism emerges as recognized human fetus. It also established the placenta relationship with the mother. Furthermore, during this period, the main organs like the arms, legs and the internal organs like the kidney, liver, lungs etc. the face, mouth, ears start to be defined better in the 8th and 9th weeks, a recognizable human body ensued . The period of the embryo is therefore a period of rapid development of the nervous system. The embryo is attached to the wall of the uterus by means of placenta , which functions as a roof, which permits the entry of foods material, oxygen and hormones and removal of carbon dioxide and metabolic wastes. The cepholocaudal and proximodistal development occur at this period.

- Foetal period

The foetal period is the final stage in prenatal life. This implies that the growing organism is called the foetus. During this period, the differentiation of these major organs continue and the organs themselves become capable of assuming their specialized functions.

Factors affecting prenatal development

• Physical factors
• Mother’s nutrition
• Use of drug
• Disease
• Age of the mother
• Emotional state of the mother