Women's Health, Infant and Children | April 2, 2015 | Author: The Super Pharmacist
Birthweight is a key indicator of infant health and a principal determinant of a baby's chance of survival and good health. At birth, most babies weigh 3000 to 3500 grams (6 to 8 pounds). Low birthweight has been defined by the World Health Organization (WHO) as weight at birth of less than 2,500 grams (5.5 pounds). This practical cut-off for international comparison is based on epidemiological observations that infants weighing less than 2,500 g are approximately 20 times more likely to die than heavier babies.
Babies born in remote areas and babies born in the lowest socioeconomic groups were more likely to be of low birthweight than babies born in major cities and babies born in the highest socioeconomic groups. It is widely recognised that weight at birth is an important indicator of foetal and neonatal health for both individuals and populations. Birthweight in particular is strongly associated with foetal, neonatal, and postneonatal mortality, inhibited long term growth and cognitive development, and chronic diseases later in life.
Birth weight is determined by two processes: the duration of gestation and the rate of foetal growth. A baby’s low weight at birth is either the result of preterm birth (before 37 weeks of gestation) or of restricted foetal (intrauterine) growth. Thus, a fetus or newborn can have a birth weight of less than 2,500 grams either because he/she is born early (preterm birth) or is born small for his/her gestational age due to intrauterine growth restriction (IUGR).
Risk factors for preterm birth include the following:
Age and certain medical conditions in the mother:
Certain lifestyle and environmental factors can also be a risk factor. These includie
Risk factors for IUGR (intrauterine growth restriction) include certain medical conditions in the mother, maternal lifestyle factors, certain medications, and congenital foetal abnormalities. The three major risk factors that account for nearly two-thirds of all growth-retarded infants (IUGR) are cigarette smoking during pregnancy, low maternal weight gain and low pre-pregnancy weight.
Medical conditions that predispose to IUGR:
Maternal factors which may cause IUGR include:
Congenital causes of IUGR include:
Studies have demonstrated higher rates of both major developmental handicaps such as cerebral palsy, mental retardation, blindness, and deafness, and less severe developmental handicaps such as learning disabilities and attention deficits, in children born preterm and/or with low birth weights. Research has consistently demonstrated a greater risk for learning-related problems in preterm, low birth weight children as they progress through infancy, preschool, and elementary school. Studies have also indicated a greater incidence of social-emotional and behavior problems associated with prematurity and low birth weight, such as internalising (e.g. depression, anxiety) and externalising (e.g. aggression) problems. LBW has also been found to be associated with increased risk of cardiovascular disease, hypertension, type 2 diabetes mellitus, and stroke. The associations are present across populations, and research has identified plausible biological mechanisms that mediate the associations.
Unquestionably, prenatal medical care can benefit certain mothers and their babies enormously. All women, pregnant or not, should get preventive and regular medical care.
But standard prenatal care cannot be expected to improve aggregate birth outcomes because most treatable medical conditions during pregnancy affect only a small proportion of women. A recent comprehensive review found no evidence that prenatal educational or psychosocial services, home visiting programs, or any medical interventions, even those to prevent infections, prevented either preterm birth or fetal growth retardation.
One promising way to reduce aggregate rates of low birth weight is to reduce smoking and improve nutrition.
Many early intervention programs have been developed to enhance the cognitive development of low birthweight infants and to improve their school readiness. A broad review of such interventions found modest success overall, with the most effective programs involving parents as well as children.
One such “two-generation” intervention, the Infant Health and Development Program (IHDP), targeted low birthweight premature infants and provided family support, including home visits and parent group meetings. Researchers have evaluated the effects of the IHDP program. One study found that the mean IQ of the intervention group at age three was 93.6, while that of the control group was 84.2; and that heavier low birth weight infants benefited more than lighter infants (those weighing less than 2,000 grams). Children whose mothers had a high school education or less gained more from the intervention than those whose mothers had attended college, with the latter showing no significant enhancement in IQ scores at age three.
Several studies found that the intervention improved cognitive scores at ages twenty-four months and thirty-six months, and one found lower (more favorable) behavior problem scores at twenty-four and thirty-six months. Children who had large gains on IQ score, cognitive skills, school achievement, and behavior at age three, however, generally did not sustain the gains at age eight, although the heavier low birth weight intervention group still outscored the control groups on measures of cognition and school achievement. A recent review of interventions targeting socially deprived families concluded that home visits accompanied by early stimulation in the neonatal unit, as well as by preschool placement, appeared to improve the cognitive development of low birthweight and premature children.
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