Prenatal development

Prenatal development is an awesome and remarkable event that occurs before birth. It is a very important developmental process because it set the stage for future development. Prenatal development starts with an individual cell called the zygote and ends after nine months or 38 weeks or 266 days. A zygote is a fertilized ovum that is made up due to the fertilization process. The end result of prenatal development is complicated newborn that is made up of billions of cells.

Prenatal development occur mainly in three stages that are
1.  Germinal stage
2.   Embryonic stage
3.   Fetal stage

Germinal stage

This step begins when an egg and sperm unite in the fallopian tube. When the sperm meets an egg then it is known as a fertilized egg. The fertilized egg is known as a zygote. The zygote then moves toward the uterus. Cell division begins in them twenty-four to thirty-six hours after the conception.

After the conception, mitosis begins in it and the zygote first divides into two cells, 4 cells, 8 cells, 16 cells and so on. When the division of the zygote reached the eight cells stage the cell differentiate and take on certain characteristics.

As the division continues the cells are divided into two masses that are the outer cell mass and the inner cell mass. The outer cell mass will become placenta in the future while the inner cell mass will form the actual embryo.

Cell division continuous and blastocyst is formed. The blastocyst consists of three layers that are the ectoderm, endoderm, and mesoderm.

The blastocyst then reaches the uterus and attached to the uterine wall. This process is known as implantation.

After the successful implantation hormonal changes occur in women that halt the normal menstrual cycle of a female.

Embryonic stage

The embryonic stage begins at the start of the third week after the conception. The three layers are formed and each layer will make the important body parts in the future. A neural tube will be formed. The neural tube will later develop into the CNS. CNS includes the brain and spinal cord.

Around the fourth week of the development, the head begins to form. Eyes, nose, the ears also start developing. The heart starts to pulse.

Buds will appear that will form legs and arms in the future. By the end of embryonic, the basic structure of CNS has been established

Fetal stage

This period begins from the 9th week and lasts until birth. In the fetal period, the structures and systems of the body that start developing in the embryonic stage will be developed completely. Legs and arms are formed. Brain completely developed. Blood vessels, blood cells are formed. Various system of the body is formed such as the human skeleton system, circulatory system, and immune system, etc. But there are some structures and system whose development is not completed. These structures complete their development in the postnatal period of development.

Another classification of prenatal development is that it is divided into periods that are
1. Embryonic period
2.  Fetal period

The embryonic period is then divided into a pre-embryonic period and proper embryonic period.

According to the 2nd classification, the prenatal period is divided into three stages that are
1. Pre-embryonic period
2.  Embryonic period
3.  Fetal period.

Postnatal development

Postnatal development extends from birth to twenty-five years. The postnatal development is divided into five stages that are

1. infancy
2. Childhood
3.  Puberty
4.  Adolescence
5.  Adulthood


The infancy period extends from birth to at least 12 months and newborn during this time period is termed as an infant. In the infancy period, the first four weeks is very important and very critical for the newborn. Because the transition from the intrauterine life to the intrauterine life requires many changes especially in the cardiovascular and respiratory system.

In the infancy period, rapid growth occurs. The part if the infancy period in which rapid growth occurs is known is the neonatal period. Newborn baby in the neonatal period is termed as a neonate.

The care of an infant through the neonatal period is termed neonatology.


The period of childhood begins after the 1st year and extends up to the 12th year. The care of children in this period is very necessary because of the constant changes occurring in the body.

As the child grows the speed of development decreases but right before the puberty the speed of development accelerates. The accelerated growth before the puberty is known as the brutal growth spurt.


The puberty period extends from 12 to 15th year in females and from 13 to 16th years in males. During this period physical growth occurs at very high speed and secondary sexual characteristics are established.

The development that occurs at puberty depends upon the hormones.


The adolescence period extends from 17 to 18th year. The two main features of this period are rapid physical growth and sexual maturation. The male gonads start secreting testosterone while the female gonads start secreting estrogen. During this period the person becomes capable to reproduce.


The adulthood period extends from 19 to 25 years. During this period development are completed. Organs are fully developed at the end of this period. Ossification of bones is also completed during this period.


Prenatal development is a type of development that occurs before birth it is classified in two ways. In the first method, the prenatal period is divided into three stages that are the germinal stage, the embryonic stage, and the fetal stage. In the second method, the prenatal period is classified into three stages that are, pre-embryonic period, embryonic period, and the fetal period. Postnatal development is a type of development that occurs after birth. the postnatal period is classified into five stages that are infancy, childhood, puberty, adolescence, and adulthood. the infancy period extends from birth to 12 months, childhood extends up to 12th-year, puberty extends from 13 to 16th year, adulthood extends from 16 to 18th year, and adolescence extends from 19 to 25th year. both types of development are very important because any disturbance in these processes will cause huge damage that will last up to death.