Belinda Fender
Chapter 2- Related Activity: 3. Identifying the Three Phases of Prenatal Development
The Journey Begins
What is prenatal development? The book defines prenatal development as “the many
changes that turn a fertilized egg into a newborn human.” Often times when an individual thinks
of pregnancy he or she usually considers how much the mother’s body changes. In contrast,
though, many fail to realize how much the baby’s body is changing. The baby does not just
appear in the mother’s stomach, the baby goes through continuous changes to morph into the
wonderful and unique human being that everyone sees after birth.
During the first two weeks called the zygote period, the baby is conceived. Although one
cannot see from just looking at the mother, a baby is already in the making. The initiation of
pregnancy happens when a mother’s egg gets fertilized; this occurs when the male’s sperm enters
a woman’s fallopian tubes in the presence of an egg. Once the sperm finally enters the egg, the
fertilization process is finished. Will the baby be a boy or girl? Even though the mother will not
be able to tell yet, the gender of the baby has already been determined. During fertilization, “the
nuclei of the egg and sperm fuse and the two independent sets of 23 chromosomes are
interchanged.” If the combination of the chromosomes is ‘XY’ the offspring will be a boy; if the
combination of the chromosomes is ‘XX’ the offspring will be a girl. The mother, on the other
hand, will just have to wait a while longer to learn the gender, or maybe even the fact that she is
pregnant. Usually, a woman knows she is pregnant when her menstrual cycles stop because of
hormonal changes; this is the body’s way of signaling to the soon to be mother that she has
conceived. This process in which “the zygote burrows into the uterine wall and establishes
connections with a woman’s blood vessels” is called implantation. It usually takes implantation
about a week to finally release the hormones to stop menstruation. This implantation, along with
“differentiation of cells, mark the end of the zygote period.”
Development, however, is far from over after the zygote period. The offspring will go
through a process called the embryo period which lasts from week three to eight. Here, the baby
will gain some of the necessities to live such as the internal organs. The body structure also
begins to form during this time. These body structures and organs are developed within three
layers known as the ectoderm, the mesoderm, and the endoderm. The ectoderm “becomes hair,
the outer layer of skin, and the nervous system;” the mesoderm “forms muscles, bones, and the
circulatory system;” the endoderm “forms the digestive system and lungs.” All that is left to
complete the embryo period is the specialization of the cells which helps the baby look more like
a human and less like a salamander.
Now that the offspring looks like a human and has the vital organs needed to live,
mothers endure the last and the longest period. The fetus period lasts from week nine to week
thirty-eight; this is when the fetus develops bones from cartilage. The most change can be seen
during this period, and for that reason, this will be the most memorable to the mother. Perhaps it
is because the mother begins to feel her baby moving. During this period, “all regions of the
brain grow – particularly the cerebral cortex, the wrinkled surface of the brain that regulates
many important human behaviors.” The baby also gets covered with a substance called vernix
around month five or six. The vernix covers the baby’s thickened skin and protects it while in
the amniotic fluid. Then, around weeks twenty-two to twenty-eight the mother is able to have a
sigh of relief. The fetus has now reached the age of viability; this means if the baby is born now,
it still has a chance to live because most of the baby’s systems are functioning well. However,
being born this early will still cause the baby to be under intensive neonatal care.
It is amazing to think about everything that fetuses go through in order to become the
humans seen walking down the street daily. Many outsiders fail to realize how much change the
fetuses endure, thinking of only the mother’s changes. However, now with a new scope of view
on the process, maybe individuals will realize the miracles of having a baby. How wonderful is
it that a woman can house a baby inside of her until it has morphed into the human that society
knows and loves?
References:
Kail, R., & Cavanaugh, J. (2010). Human development: A life-span view (5th ed., p. 53-58,639.)
Reflection
Throughout my paper, I describe the timing and the major events associated with the
period of the zygote, embryo, and fetus. Describing these three stages in my paper helped me to
realize that I did not know how much a fetus actually changes inside the womb. I always knew
that drastic changes occurred, but I did not realize the length of time it takes to go through each
stage of development. I thought that within the first couple months the baby had already gained
its vital organs and all other aspects needed to live. Then, the rest of the time spent inside the
womb was used to let the organs mature and “practice” working. Instead, babies develop new
parts, organs, and structures at different times of pregnancy. It is amazing to me that I went
through all these changes myself, and one day I will hopefully be housing and protecting my
own baby so that it too can develop at different stages just as I developed. I now understand why
mothers generally have a rough time controlling hormones during pregnancy. Changes are
happening within mothers on a daily basis, but not only do they have to endure and experience
changes to their body, but to their baby’s body as well. With this newly learned knowledge, I
hope to look at pregnancies and births differently. I hope to view every birth as being a complex,
miracle. Not only do I hope to see the miracle in concern with a new life being brought into the
world, but a miracle in relation to a mother’s body being able to carry a baby, endure all changes,
and produce a healthy human as the outcome.