premature neonateOne of the leading causes of neonatal and infant mortality is prematurity and/or low birth weight. Advances in medical care mean fewer deaths, but more reports of live births, resulting in a leveling off of mortality rates. According to a study published in the journal Pediatrics, researchers from the University of Alabama claim an increase in mortality is paralleled by an increase in live birth reports of previously underreported neonates.

Neonatal mortality is defined as death occurring in the first 28 days of life as compared to infant mortality, which is defined as death occurring before the first birthday. Advances in medical care and technology mean doctors are able to keep smaller, more premature neonates (weighing in at less than 1.1 pounds at birth) alive, but it also means more live births are reported. In the past, neonates born extremely premature or extremely low birth weight may not have been reported as a live birth. With more small neonates surviving, more doctors are reporting the live births.

Researchers also noted a leveling off of the steep decline in infant mortality rates. In 1915 about 100 infant mortalities were reported per 1,000 births each year. That number dropped to less than seven deaths per 1,000 births in 2008. The same sharp decline was noted in neonatal mortality rates which dropped from about 21 deaths per 1,000 in 1950 to less than five deaths per 1,000 in 2008. When researchers looked more closely at the numbers, there was a clear plateau between 2000 and 2008 when neither infant nor neonatal mortality rates changes significantly. However, there was a sharp rise in premature births and low birth weight infants from 1983 to 2005 which could have affected mortality rates.

When researchers took weight and gestational age into consideration, neonatal and infant mortality rates showed significant decline, something researchers were happy to find. According to the study’s lead author, Dr. Wally Carlo, “The analysis clearly showed that the leveling off of infant and neonatal mortality is due to the increased proportion of extremely low birth weight and preterm infants born in the U.S. We were pleased to find that infant and neonatal mortality have continued to decrease, when birth weight and gestational age specific analysis is done, meaning normal birth weight and term infants are surviving past their first birthday in increasing numbers in the U.S.”

Source: Carissa Lau, Namasivayam Ambalavanan, Hrishikesh Chakraborty, Martha S. Wingate, and Waldemar A. Carlo. Extremely Low Birth Weight and Infant Mortality Rates in the United States. Pediatrics, 2013; DOI: 10.1542/peds.2012-2471