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 Unit 3 Introduction - Prenatal Development, Birth, and Infancy

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PostSubject: Unit 3 Introduction - Prenatal Development, Birth, and Infancy   Mon Apr 25, 2011 7:52 am

Introduction



In this unit, we will examine the stages of prenatal development and
the role of the environment, including teratogens, which are
environmental agents that cause developmental abnormalities. Most of us
are familiar with the effects of two common teratogens, nicotine and
alcohol, on prenatal development.


Prenatal development begins with the germinal stage, in which the
ovum is fertilized by a sperm cell and forms a zygote at conception.
The zygote travels to the uterus via the fallopian tube, where it
begins the implantation process in the uterus by the seventh to ninth
day after conception. The germinal stage ends at around two weeks after
conception (Berk, 2008).


During the embryonic stage, which occurs from the second week until
the eighth week, major organs and their structures develop. The embryo
is particularly susceptible to teratogens (which may be agents, such as
drugs or alcohol, and conditions, such as poverty) depending upon which
organs or structures are developing at the time of exposure. Exposure
to specific teratogens may negatively impair prenatal development and
even result in birth defects. The heart begins to beat at the fourth
week, and the digestive system develops (Berk, 2008).


At six weeks, the reproductive system differentiates gender. Like
other areas of prenatal development, this system is affected by genetic
and physical factors inside and outside the embryo, as well as the
outside world. During the fetal stage, from eight weeks to birth, major
systems and organs continue to develop. At approximately nine to 12
weeks, sucking and swallowing reflexes develop, extremities such as
fingers and toes become more defined, hair grows on the head, and the
liver can produce red blood cells. At 20 weeks, individual differences
in fetal activity develop, and these correlate with activity and
responsiveness after birth. At 24 weeks, the fetus is able to hear.
Fingernails and toenails develop, and the skin is protected by a waxy
coating (Gross, 2008; Berk, 2008).

By 28 to 32 weeks, the eyelids can open and close, the bones are
soft but developed, and there is an increase in activity, sound
responsiveness, and the basic ability to regulate body temperature. By
38 to 40 weeks, a fetus is considered full term (Gross, 2008).


In the first few weeks after conception, the origins of the brain
begin to develop, and rapid brain growth continues in the fetal stage,
especially during the final two months. Brain development continues
after birth, and is contingent upon early life experiences (Gross,
2008, Berk, 2008).

The interrelationship of complex elements is a rich area of continuing research and controversy.


The period of gestation is subject to many maternal, familial, and
environmental influences. Some of these influences may create
vulnerabilities to psychological difficulties (such as shyness or
schizophrenia) or physical ailments (such as genetic diseases) after
birth (or much later). Exposure to specific teratogens may also
negatively impair prenatal development and may result in birth defects.
In addition, the prenatal environment in combination with external
environmental factors contributes to the etiology of a child's
temperament. By identifying and understanding major prenatal factors,
the psychologist or counselor is better equipped to provide advice and
counsel to parents before and after birth .


Educational programs that address parent decision-making with
reference to teratogenic risk factors must be tempered with sensitive
counseling methods. Psychologists and counselors working with
parents-to-be, therefore, will find it essential to become familiar
with the material in this unit (Berk, 2008).


Approaches to childbirth are not the same in all cultures. For
example, in Western nations, labor and delivery are often in the domain
of doctors and hospitals. In other nations, providers who are not part
of the medical community often help women through childbirth. But
approaches to childbirth are not necessarily monolithic. For example,
since the 1960s, women have challenged traditional medical practices in
favor of more "natural" childbirth options. Such options include birth
centers or home births. Birth centers are more homelike settings that
allow for more maternal control over delivery options and opportunities
to include family, as well as early infant-parental contact after birth
(Berk, 2008).

Natural childbirth and prepared childbirth are different medical
approaches, both of which are intended to make the childbirth process
to be as rewarding and physically comfortable as possible. The typical
natural childbirth process involves labor and delivery education,
relaxation and breathing techniques, and a labor coach. Social support
during childbirth has been found to result in fewer medical
complications, such as shorter labors, and less cesarean procedures
(Sauls, 2002). But cesarean deliveries (surgical births) have
dramatically risen throughout the world mainly due to the medical
control over the childbirth process (Berk, 2008).

Birth complications result from a diverse number of factors,
including lack of prenatal care, medical conditions that cause
problematic pregnancies, and social factors such as poverty. One common
birth complication is oxygen deprivation, known as anoxia. It is caused
by placenta abruption, or premature separation of the placenta, which
may be due to the effects of teratogens such as cocaine and nicotine.
These teratogens cause constriction of the blood vessels and abnormal
placenta development (Berk, 2008).


Anoxia may also result from squeezing of the umbilical cord. In
cases where delivery seems normal, infants may be born not breathing.
Healthy newborns can survive without breathing for about 10 minutes,
due to a reduction in metabolic rate that conserves limited oxygen, but
oxygen deprivation for a longer period may result in brain damage.
Moreover, secondary damage may occur hours after the initial brain
damage. Researchers are testing ways to prevent this type of brain
injury (Berk, 2008). According to research (Hopkins-Golightly, Raz,
& Sander, 2003), newborns who suffer anoxia during labor and
delivery display cognitive and language delays in later childhood.
However, children with mild to moderate anoxia tend to gradually
improve when their environments are supportive.


Another life-threatening condition, placenta previa, involves
placenta detachment in the third trimester. Both may only occur in 1 to
2 percent of all births, but they involve serious health risks and
often make emergency cesarean deliveries necessary (Berk, 2008).


Infants that are born three weeks or more prior to end of full term
(a 38-week pregnancy), or who weigh less than 5 and one-half pounds,
are considered premature. Preterm infants are born several weeks before
their due date, and their weight may be appropriate depending on amount
of time spent in the uterus. Small-for-date infants are below the
expected weight given the length of pregnancy. Some of these infants
are actually full term, while others are extremely underweight or low
birth weight, and are considered preterm. Small-for-date infants are
particularly vulnerable to serious health problems, such as infections,
brain damage, and death. Those that survive have been found to have
academic, cognitive, and intellectual difficulties in later childhood
(Hediger et al., 2002; O'Keefe et al., 2003).


Although there are major biological and cognitive risks related to
low birth weight, some research (Hack & Klein, 2006) has found that
environments that are rich in education, health care, and parenting
appear to mitigate these risks. In a Canadian study that followed low
birth weight infants until their mid-twenties, these infants resembled
their normal birth weight peers across a host of outcomes (such as
social skills, employment, and education).


Birth weight is the single best predictor of infant survival and
developmental outcomes, and has been linked with poverty, teratogens,
and lack of prenatal care (Berk, 2008). The U.S. has one of the highest
rates of low birth rates of the industrialized nations. About 1 in 13
American infants are born underweight (Children's Defense Fund, 2006).
For newborns weighing three and one-half pounds or less, developmental
difficulties continue into childhood and beyond (Grunau, Whitfield,
& Fay, 2004).


The consequences for caring for premature infants are numerous,
depending on the context into which the infants are born. The
infant-parent relationship is crucial in child outcomes, as are family
circumstances, such as social support and adequate economic stability
to provide for the infant's needs (Berk, 2008).


References


Berk, L. E. (2008). Infants, children, and adolescents (6th ed.). Boston, MA: Pearson Education.


Children's Defense Fund (2005). The state of America's children: 2005. Washington, DC. Retrieved from http://www.childrensdefense.org/site/DocServer/Greenbook_2005.pdf?docID=1741


Grunau, R. E.,Whitfield, M.F., & Fay, T.B. (2004). Psychosocial and academic characteristics of extremely low birth weight adolescents who are free of major impairment compared with term-born control subjects. Pediatrics, 114(6), E725-E732.


Hack, M., & Klein, N. (2006). Young adult attainments of preterm infants. Journal of the American Medical Association, 295, 695696.


Hediger, M. L., Overpeck, M. D., Ruan, W.J., & Troendle, J. F. (2002). Birth weight and gestational age effect on motor and social development. Pediatric and Perinatal Epidemiology, 16(1), 3346.


Hopkins-Golightly,T., Raz, S., & Sander, C. J. (2003). Influence of slight to
moderate risk for birth hypoxia on acquisition of cognitive and
language function in the preterm infant: A cross-sectional comparison
with preterm-birth controls. Neuropsychology, 17(1), 313.


O'Keefe, M. J., O'Callaghan, M., Williams, G.M., Najman, J.M., & Bor, W. (2003).Learning, cognitive, and attentional problems in adolescence born small for gestational age. Pediatrics, 112(2), 301307.


Sauls, D. J. (2002). Effects of labor support on mothers, babies, and birth outcomes. Journal of Obstetric, Gynecologic, & Neonatal Nursing, 31(6), 733741.

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