The unborn developing baby from eight weeks until birth is called a fetus. From conception to birth, the fetus should have developed all the sense essential for its survival. This essay focuses on the development of these senses throughout gestation. A few factors that may affect the development of the fetus in general may include nutrition, alcohol and drugs, smoking, prenatal care and age.
The womb is the organ in which fetus development occurs and is designed to offer optimal conditions for this development. It must and does therefore offer an interactive relationship with the developing fetus. Owing to this, it is not surprising that touch is the first human sense that develops. It plays a huge role as a major factor affecting fetal activity, communication and feedback. At eight weeks, the sense of touch starts to become more profound in that there are maneuvers that ensure protection of the fetus from any kind of injury. Experiments show that these maneuvers by the fetus will avoid even a stroke by something as tiny as a single hair.
This kind of sensitivity is most evident at the cheeks at first but later as the fetus develops ,sensitivity to touch then grows to other parts of the embryonic body including the genital area in about 70 days ,palms and sole in eleven and twelve weeks respectively. The above outlined areas eventually end up with the highest concentration of sensory nerves in adulthood. The buttocks and abdomen will have developed sensitivity at about seventeen weeks and at week 32 most of the body reacts to the stroke of a hair. During the last few months of gestation the fetal skin is covered with vernix caseosa which acts as protection against bacteria (Hoath, Pickens, & Visscher, 2006).
The sense of motion occurs about three weeks after conception and occurs in a rhythmic fashion.It is an awesome phenomenon as the heart beats while most of its components are still under construction. This demonstrates that body parts become operational as they become available and that the fetus is not yet a full person(Lovering, 2007) The head, arms and legs start achieving motion at about six or seven weeks. At ten weeks, the fetus can now move its head, its hands can now move to face and back and the mouth can open and close to swallow. By the 14th week, all fetal body movements manifested during the pregnancy period are now all easily detectable.
It is also during this period that the jaws begin to move and breathing movements are also already evident. From this stage of development, the fetal movements are present and may be in reaction to events or just spontaneous.
Spontaneous movements begin a lot earlier in development but reaction movements occur due to sensitivity to the surroundings of the fetus. At 10 to 15 weeks, semi circular canals are built to help maintain balance because any sudden movement of the mother through things like coughs or laughs trigger the fetus to move; within seconds of the mother’s movement. The relationship between the mothers salivary cortisol levels and fetus’ motor activity have been observed and research indicates that higher cortisol levels result in wider fetal movements at 32 weeks (DiPietro, Kivlighan & Costigan, 2009).
The sense of taste comes into play at 14 weeks. Researchers have reason to believe that tasting starts at this stage. Tests carried out reveal that the fetus swallows more with sweet tastes and less with sour tastes. The amniotic fluid is composed of many elements and substances with different tastes for proteins, acids and salts. Tests carried out at birth also show taste preference for the various tastes (Arias. Chotro, 2007).
Until recently the sense of smell was assumed not to come into play during gestation because of the absence of air. The nose is constructed between the eleventh and fifteenth weeks and numerous compounds are exchanged between the placenta and the amniotic fluid (Kiserud, Acharya, 2005). These compounds relay to the fetus different tastes and odors. Schaal, Orgeur, and Rogan (1995) strived to attest to the fact that that the ability to discern different odors could be acquired in the womb.
This, they attributed to the presence of about 120 odiferous compounds in the amniotic fluid. These encounters with odorants from the amniotic fluid and via the placenta set up the sense of smell for future interaction with odors. Observation reveals that newly born babies are attracted to the smell of breast milk despite the fact that they have no previous knowledge of it.
Many studies have been carried out and reveal that outside sounds actually reach the womb. Most of these voices in fact reach the womb without much distortion and have been found to have an immense impact on the heart rate of the fetus. A short stimulus can trigger a change in heart rate lasting up to 60minutes.Certain sounds have been found to have an effect on metabolism of babies. “Brahm’s Lullabye,” played in a premature baby nursery led to a more speedy increase in weight than that caused by voice sounds applied at the same time and fashion (Harden, Newton, 2006).
Researches reveal that responsive hearing commences at 16 weeks. This starts way before the ears are wholly developed at 24 weeks (Martini, 2008). This is truly phenomenal and demonstrates the fact that during gestation, processes and body functions can begin and develop before development of the organs associated with these functions. Hearing provides a particularly clear example as it begins almost 24 weeks before birth and continues for about 8weeks before the full development of the ears.
The other sense that is perhaps most dear to us after birth is vision. It is vital for babies after birth but develops extensively during pregnancy. Reviews show that vision is excellent the first few months after birth (Berenbrink, 2007).
Tests also show that unborn babies have many vision capabilities. At 33-34 weeks, the fetus capabilities march those at 40 weeks. Fully grown babies have surprising visual capabilities as they have acuity, are sensitive to contrast, can accommodate, have color vision and are sensitive to flicker and motion patterns.The eyes remain closed during gestation up to the 26th week. The fetus however remains sensitive to light and reacts to light with variation in the heart rate.
All the mentioned developments in senses do not occur in isolation. They happen through networking and coordination (DiPietro, 2005). It has been demonstrated that the gustatory and olfactory systems are closely related, skin and bones are allied to hearing and vision shows functionality even with closed eyes during gestation. Fetuses react to pain with body movements and increased breathing as they lack the capacity to react aurally.
In conclusion all body senses develop early in the fetus and most functions begin working even before their respective organs are fully constructed. By the end of gestation, all body organs and senses are fully developed and functional in readiness for independence.
References
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DiPietro, J. A., Kivlighan,K. T., & Costigan, K. A.(2009). Fetal motor activity and maternal cortisol. Developmental Psychobiology, 51, (6), 505-512.
DiPietro, J.A. (2005). Neurobehavioral assessment before birth. Mental Retardation and Developmental Disabilities Research Reviews, 11(1), 4-13.
Harden, M. V., & Newton, L. A. (2006). Olfactory imprinting is correlated with changes in gene expression in the olfactory epithelia of the zebra fish.Journal of Neurobiology, 66 (13), 1452-1466.
Hoath ,S. B., Pickens, W. L., & Visscher, M. O. (2006). The biology of vernix caseosa. International Journal of Cosmetic Science, 28(5), 319-333.
Kiserud, T., & Acharya, G. (2006).The fetal circulation. Prenatal Diagnosis, 24 (13), 1049-1059.
Korthank, A. J., & Robinson, S. R. (2006). Effects of amniotic fluid on opioid activity and fetal responses to chemosensory stimuli. Developmental Psychobiology, 33(3), 235-248.
Lovering, R.P. (2005). Does A Normal Fetus Really Have A Future Of Value? A Reply to Marquis. Bioethics, 19(2), 131-145.
Martini, F. (2008). Fundamentals of anatomy and physiology. (7th Ed). San Francisco, USA: Pearson Benjamin Cummings.
Sun, J.C., & Hsia, P.H. (2008).Women of advanced maternal age undergoing amniocentesis: a period of uncertainty. Journal of Clinical Nursing, 17, (21), 2829-2837.