Stress and low birth weight
A second area of developing convergence concerns
the effects of stress on infant birth weight and/or
LBW, reviewed recently by Dunkel Schetter and
Lobel [9&&]. Again these studies can be organized
by type of stressor. Evidence suggests that ‘major
life events’ somewhat consistently predicted
fetal growth or birth weight, whereas measures of
‘perceived stress’ had small or nonsignificant effects.
‘Chronic stressors’, however, have been even more
robust predictors of birth weight. For example,
unemployment and crowding predicted 2.0 to
3.8 times the risk of LBW among low-income
women in one study [13]. An important source of
chronic stress is ‘racism or discrimination’ occurring
both during the pregnancy and over a woman’s
lifetime [14]. Racism and discrimination contribute
to birth outcomes independently of other types of
stress [15]. A growing number of studies have
demonstrated that racism and discrimination
prospectively predict birth weight, particularly in
African–American women [16]. Although this
literature has focused mainly on women in the
USA, it is relevant to minority women in other
countries [17].
In summary, chronic strain, racism, and related
factors such as neighborhood segregation are significant
risk factors for LBW [18]. Of note, investigations
of chronic stress and racism do not usually
take into account depressive symptoms. Yet, depression
may be an important mechanism whereby
the effects of exposure to chronic stress and racism
influence fetal growth and birth weight, likely
via downstreamphysiological and behavioral mechanisms
[9&&].