80 ChapTer 3 Development Over the Life Span
of having autism or bipolar disorder (Frans et al.,
2008; Kong et al., 2012; Reichenberg et al., 2006).
During a woman’s pregnancy, some harm-
ful influences can cross the placental barrier
(O’Rahilly & Müller, 2001). These influences in-
clude the following:• Rubella (German measles), especially early in
the pregnancy, can affect the fetus’s eyes, ears,
and heart. The most common consequence is
deafness. Rubella is preventable if the mother
has been vaccinated, which can be done up to
3 months before pregnancy.
• X-rays or other radiation, pollutants, and
toxic substances can cause fetal deformi-
ties and cognitive abnormalities that can last
throughout life. Exposure to lead is associated
with attention problems and lower IQ scores,
as is exposure to mercury (found most com-
monly in contaminated fish), pesticides, and
high air pollution (Newland & Rasmussen,
2003; Perera et al., 2006; Raloff, 2011).
• Sexually transmitted diseases can cause men-
tal impairments, blindness, and other physical
disorders. Genital herpes affects the fetus only
if the mother has an outbreak at the time of
delivery, which exposes the newborn to the vi-
rus as the baby passes through the birth canal.
(This risk can be avoided by having a cesarean
section.) HIV, the virus that causes AIDS, can
also be transmitted to the fetus, especially if the
mother has developed AIDS and has not been
treated.
• Cigarette smoking during pregnancy in-
creases the likelihood of miscarriage, prema-
ture birth, an abnormal fetal heartbeat, and an
underweight baby. The negative effects may last
long after birth, showing up in increased rates of
infant sickness, sudden infant death syndrome
(SIDS), and, in later childhood, hyperactivity,
learning difficulties, asthma, and even antisocial
behavior (Button, Thapar, & McGuffin, 2005).
• Chronic or severe maternal stress can affect
the fetus, increasing the risk of later cognitive and
emotional problems and vulnerability to adult
diseases such as hypertension (Talge, Neal, &
Glover, 2007; Weinstock, 2005). Babies of moth-
ers who developed posttraumatic stress disorder
in the aftermath of the World Trade Center at-
tacks on 9/11 were more likely to have abnormal
cortisol levels themselves at 1 year of age and also
to weigh less at birth, both indicators of future
health problems (Yehuda et al., 2005).growing embryo’s link for food from the mother. It
allows nutrients to enter and wastes to exit, and it
screens out some, but not all, harmful substances.
At eight weeks after conception, the embryo
is only 1 1/2 inches long. During the fourth to
eighth weeks, in embryos that are genetically
male, rudimentary testes secrete the hormone
testosterone; without it, the embryo will develop
to be anatomically female. After eight weeks, the
organism, now called a fetus, further develops the
organs and systems that existed in rudimentary
form in the embryonic stage.
Although the womb is a fairly sturdy protec-
tor of the growing embryo or fetus, the prenatal
environment—which is influenced by the mother’s
own health, allergies, and diet—can affect the
course of development, for example by predispos-
ing an infant to later obesity or immune problems
(Coe & Lubach, 2008). Most people don’t real-
ize it, but fathers, too, play an important role in
prenatal development. Because of genetic muta-
tions in sperm, fathers older than 50 have three
times the risk of conceiving a child who develops
schizophrenia as fathers younger than age 25 do
(Malaspina, 2001); teenage fathers have an in-
creased risk that their babies will be born prema-
turely or have low birth weight; babies of men
exposed to solvents and other chemicals in the
workplace are more likely to be miscarried or still-
born or to develop cancer later in life; and a child
with an older father has an increased probabilityDevelopmental psychologists study people across the
life span. They would have a living laboratory with this
six-generation family: Sara Knauss, age 118 ( center);
her daughter, age 95 (right), her grandson, age 73
( center), her great granddaughter, age 49 (standing with
her dad), her great-great granddaughter, age 27 (on the
floor), and her great-great-great grandson, age 3.