PRENATAL ENVIRONMENTAL
INFLUENCES:
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⚫ The previous discussion of prenatal development refers to normal prenatal development. However, from time to time, certain factors may
disrupt this normal development, with the result that the child's physical and mental health and development could be affected in varying degrees.
⚫ The causes of congenital abnormalities (i.e. present at birth) may be ascribed to about 20% heredity, 10% prenatal environmental
factors, while 70% are unknown or ascribed to the interaction between environmental or genetic factors (Cilliers,
2011; Cleveland Clinic, 2012).
Teratogen
Any external factor or process that has a negative effect on the normal development of an unborn child
⚫ In the past, the term had a strong medical connotation and referred only to the effect of, for example, medications, drugs and maternal
illnesses.
⚫ Laterally, authors and researchers in especially the humanities include variables such as maternal age and emotional state of the pregnant
woman in their definitions of teratogens.
The term Behavioural teratology was coined to
refer to the study of the effect of teratogens on the behaviour of pre- and post-natal children.
⚫ Next, we shall discuss some of the most important teratogens: the age of the parents, nutrition of the mother, radiation, illnesses during
pregnancy, medication and drugs, and the emotional state of the mother.
⚫ It is important to realise that several factors and principles could determine the effect of teratogens on the unborn child (Kail, 2012; Santrock,
2013):
Time of exposure. Teratogens cause more damage at certain phases of development than during others. The embryonic phase is
usually more vulnerable than the fetal phase.
Genetic vulnerability. The nature and severity of the abnormalities is dependent on the genetic makeup of both the mother and
the child. It seems that some mothers and children are genetically more vulnerable than others are. This could explain why there are more
abnormalities in one child than in another, although their mothers used alcohol and tobacco to the same degree.
The degree or intensity of the factor plays a role. For example, the more the mother smokes or drinks the greater the
chances are that an unborn child could be harmed.
Each teratogen has a different effect on the unborn child. Each independent teratogen thus harms an unborn child
differently. In other words, the damage is selective. For example, if a pregnant woman contracts Rubella (German measles), her baby's
limbs will be normal, but the baby will have problems with its vision, hearing and heart. In the case of another teratogen, the limbs could be
deformed, but the child has no other physical or mental abnormalities.
The damage is not always evident at birth. Although especially physical deformities are noticeable after birth,
psychological problems such as cognitive deficits may appear only later in life. For example, in a study in Soweto and Johannesburg, no
significant effects of maternal stress was found at the age of two, but behavioural problems appeared at four (Ramchandani, Richter,
Norris & Stein, 2010)
⚫ Remember that abnormal prenatal development is definitely the exception rather than the rule.
⚫ Approximately 98% of pregnancies in South Africa produce babies that are psychologically and physically healthy (De Coning, 2011).
⚫ This compares favourably with international statistics.
⚫ The following prenatal environmental factors could nonetheless influence the development of the child negatively.
UNIT 2 - Prenatal development and the birth proces Page 1
, THE AGE OF PARENTS
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⚫ There is general agreement that mothers younger than about 20 or older than about 35 run a greater risk of giving birth to
children with psychological and physical defects, than mothers between these ages.
⚫ Teenage mothers are especially more susceptible to, for example, premature births, stillbirths and birth problems.
⚫ Such risks increase for mothers aged 15 and younger.
⚫ Women older than 35 who become pregnant for the first time and women older than 40, who have previously been pregnant,
tend to have longer and more difficult birth processes. Stillbirths and problems during pregnancy are also more common.
⚫ Generally speaking, the risk of a woman giving birth to a child with Down's syndrome also increases as she gets older (see Table 2.3).
⚫ However, the mother's age does necessarily have to be a negative factor.
⚫ Quite commonly, women who are older than 35 and who are in a good physical, nutritional and emotional condition, do not
experience more complications than mothers aged 20 to 35.
⚫ Therefore, it is understandable that Myrskylä and Fenelon (2012, p. 30), after having completed a comprehensive study in this regard,
declare, "The public health concern regarding maternal ages should focus on young, not old mothers."
⚫ The relatively high frequency of Down's syndrome babies amongst older mothers is possibly because their reproductive system is past its
prime.
⚫ Related aspects such as degenerated egg cells could play a significant role.
⚫ By far, the majority of women in their 40s do not have Down's syndrome babies, while women in their early 30s and even 20s do. This indicates
that other factors, not yet identified, are also involved.
⚫ Until recently, researchers have focused almost exclusively on the age of the mother, while the age of the father has been almost fully
neglected.
⚫ However, the situation is changing and factors, such as the quality of the father's sperm, are receiving research attention.
⚫ There are already strong indications that a paternal age of higher than about 40 years may increase the possibility of
fetal deaths and certain genetic disorders such as Down's syndrome (Goriely & Wilkie, 2012; Hurles, 2012).
UNIT 2 - Prenatal development and the birth proces Page 2