Understanding Psychology (10th Ed)

 PRENATAL ENVIRONMENTAL INFLUENCES 
Genetic factors are not the only causes of diffi culties in fetal development. Environmen-
tal infl uences—the nurture part of the nature–nurture equation—also affect the fetus. 
Some of the more profound consequences are brought about by  teratogens,  environ-
mental agents such as a drug, chemical, virus, or other factor that produce a birth defect. 
Among the major prenatal environmental infl uences on the fetus are the following:
• Mother’s nutrition . What a mother eats during her pregnancy can have impor-
tant implications for the health of her baby. Seriously undernourished mothers 
cannot provide adequate nutrition to a growing fetus, and they are likely to 
give birth to underweight babies. Poorly nourished babies are also more 
susceptible to disease, and a lack of nourishment may have an adverse impact 
on their mental development (Zigler, Finn-Stevenson, & Hall, 2002; Najman et 
al., 2004; Everette, 2008).
• Mother’s illness . Several diseases that have a relatively minor effect on the 
health of a mother can have devastating consequences for a developing fetus if 
they are contracted during the early part of a pregnancy. For example, rubella 
(German measles), syphilis, diabetes, and high blood pressure may each 
produce a permanent effect on the fetus. The virus that causes AIDS can also 
be passed from mother to child before birth and through breast-feeding after 
birth (Nesheim et al., 2004; Magoni et al., 2005).
• Mother’s emotional state . A mother’s emotional state affects her baby. Mothers who 
are anxious and tense during the last months of their pregnancies are more apt 
to have irritable infants who sleep and eat poorly. The reason? The autonomic 
nervous system of the fetus becomes especially sensitive as a result of chemical 
changes produced by the mother’s emotional state (Relier, 2001; Hollins, 2007).
• Mother’s use of drugs. Mothers who take illegal, physically addictive drugs such 
as cocaine run the risk of giving birth to babies who are similarly addicted. 
Their newborns suffer painful withdrawal symptoms and sometimes show 
permanent physical and mental impairment. Even legal drugs taken by a 
teratogens
Environmental agents such 
as a drug, chemical, virus, or other 
factor that produce a birth defect.
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