FIGURE 1
SOURCE: Martha Slay, Greg R. Alexander, and Mary Ann Pass.
research, current knowledge is limited about the
causes of preterm delivery. Risk factors associated
with preterm birth include cigarette smoking during
pregnancy, prior preterm birth, low prepregnancy
weight, and maternal chronic diseases; but known risk
factors account for less than one-fourth of preterm
births. The factors associated with fetal growth restric-
tion are more readily understood than those of pre-
term delivery. Cigarette smoking during pregnancy,
low maternal weight gain, and low prepregnancy
weight account for nearly two-thirds of all fetal
growth restriction and seem to be the most promising
areas for possible interventions. Other associated fac-
tors include multiple births (e.g., twins), infant gen-
der, and several factors relating to the mother,
including: birthweight, racial or ethnic origin, age,
height, infections, history of prior low birthweight de-
livery, work/physical activity, substance use/abuse,
cigarette smoking, alcohol consumption, and socio-
economic status. While prenatal care was once touted
as a highly effective means to prevent low birthweight,
more recent assessments have raised serious chal-
lenges to this assumption, leaving the matter now in
doubt.
Poverty, given its association with reduced access
to health care, poor nutrition, lower education, and
inadequate housing, may be an appreciable factor un-
derlying the risk of delivering a LBW infant. Socio-
economic status is linked to individual behaviors,
such as cigarette smoking and alcohol consumption,
and varies markedly by race and ethnicity. While so-
cioeconomic status and race/ethnicity cannot be
termed ‘‘causes’’ of low birthweight, they serve as in-
dicators of complex links between environmental,
psychological, and physiological factors that may re-
sult in higher risks of low birthweight.
The percentage of LBW infants in the United
States rose during the last two decades of the twenti-
eth century. This increase, coupled with the improved
survival of LBW infants, has heightened the need to
further understand the long-term outcomes of LBW
infants in regard to growth, development, and dis-
ease, as well as the impact these children have on the
health care system. When compared to normal birth-
weight children, LBW children have higher rates of
mental retardation, cerebral palsy, blindness, deaf-
ness, psychomotor problems, school failure, subnor-
mal growth, and health problems, which are62 BIRTHWEIGHT