A fruitful pregnancy has several stages. A male sperm fertilizes a female egg. Now this zygote must divide and develop into an embryo. This embryo becomes a fetus. After many weeks the prenatal period ends and a newborn breaths in this world.
With the fertilization of the female egg cell development of a new living creature starts. This embryo development process is orderly so we can give a timetable for the development process. There are three stages of prenatal growth:
- Germinal Stage
- The Embryonic Stage
- The fatal Stage
Periods of the Ovum
(Conception to End of the Second Week)
There is no outside source of food and all cells are taking their food from the egg yolk so the size remains unchanged and it forms a blastocyst. Internal development is rapidly taking place.
After, 10 days of fertilization implantation in the uterus wall takes place and its size is about 0.2mm in diameter.
The site of attachment is variable and not predetermined.
Now the parasite stage of the ovum starts
Period of the Embryo
(End of the Second Week to End of the Second Lunar Month)
All important external and internal features start to develop and function.
The neural tube forms that develop into the central nervous system.
Production of the neuron cells starts around 42 days and continues around the middle of the pregnancy.
Around the eighth week head begins to form and its growth is greater than the other parts of the baby.
It is a time that careful scanning can determine the sex of the to-be-baby.
Now the to-be baby measures around 1.5 to 2 inches and it weighs about 1 ounce.
Now it is the time for self-independence so all other necessary parts like the placenta, umbilical cord, and amniotic sac- develop.
Period of the Fetus
(End of Second Lunar Month to Birth)
When the cell differentiation is almost complete fetus enters the embryonic stage.
External and internal features to continue growth and development.
The new support system-placenta is fully functional.
Between the 9th and 12th week of gestation, reflexes begin to emerge.
The fetus continues to grow both in length and weight.
The end of the third month means the end of the first trimester and it is the second trimester that you can hear the heartbeat of your baby. Internal organs assumed nearly exact positions by 3rd lunar month.
Internal organs assumed nearly exact positions by 3rd lunar month.
In 28th week brain is developed to a great extent and now it resembles to the mind of a sleeping newborn baby.
Nerve cells, present since the third week, increase rapidly in number daring ate second, third, and fourth months.
From the 7th month till birth, the human fetus puts weight and gets ready for life outside the womb.
Lung muscles start expanding and contracting, ready to breathe in the outer world.
Parental Influences on Fetus
It was assumed till the 60s that the fetus is protected in the mother's womb. The placental barrier protects the fetus from the harmful influences of the other world. The harmful influence could be dangerous rays, stress, noise, viruses, pungent smells, and a lot more. This myth was not true. It was proved that these influences deeply affect the fetus. Some of these influences can result in any deformities of the fetus.
There are critical periods of development during the prenatal stage. Any strong outer influence can badly affect the to-be newborn.
During the early stage, a defective zygote is naturally aborted. But in the complex and later stages of development, this does not happen. With the negative influences the to-be baby continues to develop. A time comes when the cell division slows down, the size of the cells increases and organs develop. Continuous exposure to any negative influence will result in a defective organ.
First Three Months:
Adverse drug effects can damage the development of tissues and the body system. The branch of science that deals with the effects of external influences on the development of a fetus is known as Developmental Teratology. One of the findings of this branch is that Thalidomide Babies are exposed to drugs during this period.
The branch of science that deal with the effects of the external influences on the development of a fetus is known as Developmental Teratology.
Drugs:
Good as well as Bad Drugs have some effect on the growing fetus. Any substance that is taken in large quantities has some effect such as caffeine, antibiotics, aspirins, etc. Fetal Alcohol Syndrome is a documented abnormality.
Diseases:
German Measles and a few other diseases of the mother result in severe defects such as blindness, deafness, and nerve and brain defects in the fetus.
Hormones:
Till 1970 DES was given to mothers who have high rates of miscarriages. Female Babies born from these mothers reported a high rate of uterus cancer when adults.
Radiations & Environmental Hazards:
Repeated exposure to X-rays can negatively affect the growth of a fetus. Mussen, Conger, and Dagan 1975 studied in detail the survivors of atomic bombs in Japan, who were exposed to these radiations.
Conclusion
Thus, each and every developmental stage of a fetus is very important. It needs to be protected from the external influences. So this 266 days prenatal period is very important for the rest of the life of a being. The zygote multiplies into 200 billion cells. It is the time when the young organism is ready to come to this world.
So this 266 days prenatal period is very important for the rest of the life of a being. The zygote multiplies into 200 billion cells.