RISK FACTOR CHILD

MILD AND MODERATE PRETERM BABIES HAVE HIGH RELATIVE RISK OF DEATH DURING INFANCY

According to background information cited in the study, the World Health Organization defines preterm birth as a gestational age at birth of less than 37 completed gestational weeks. Preterm birth is recognized as a major public health problem by both clinicians and researchers because it is the leading cause of infant mortality in industrialized countries and also contributes to substantial neurocognitive, pulmonary, and ophthalmologic morbidity. Babies born at 34-36 gestational weeks are considered mild preterm; those born at 32-33 gestational weeks are classified as moderate preterm.

The researchers determined relative risk (RR, which indicates how much more frequently a given outcome occurs in those with a certain risk factor versus those without it) of death during infancy for preterm births compared with term (> 37 weeks) births. They also estimated the public health impact by determining the etiologic fraction (EF), the proportion of all cases of an outcome in the population which can be attributed to exposure to the risk factor.

Compared to babies born at term (37 or more weeks gestation), "Relative risks for infant death from all causes among singletons born at 32 through 33 gestational weeks were 6.6 in the

"Infants born at 32 through 33 gestational weeks were at high RR of infant death in both countries," they continue. "To our surprise, the largest RRs were seen in the neonatal period. For infants born at 34 through 36 gestational weeks, the RRs were somewhat lower but still substantial and statistically significant."

The authors assert that when the elevated RR of mild and moderate preterm infants is combined with their larger numbers compared to more extreme preterm births, it translates into a substantial impact at the population level. "In fact, the combined impact exceeded that of infants born at 28 to 31 gestational weeks for all causes and all three ages at death and even that of infants born at less than 28 gestational weeks for postneonatal deaths," they write.

Except for a slight reduction in neonatal deaths attributed to infection among babies born at 34-36 gestational weeks, Despite the continued reduction in gestational age-specific mortality with improvements in high-risk obstetric and neonatal care, mild and moderate preterm births continue to contribute an important fraction of infant deaths from a variety of causes," they write.

"Obstetricians should be aware of these risks when contemplating preterm induction or caesarean delivery, and pediatricians may wish to consider closer monitoring of mildly and moderately preterm infants after hospital discharge," they conclude.