This article is more than 5 years old. Information may no longer be current.
Low birth weight led to small decrease in infant mortality rates
Click Here to Manage Email Alerts
Increasing numbers of infants weighing less than 500 g and other low birth weight infants have contributed to the lack of substantial decrease in infant mortality and neonatal mortality rates in the United States, new research suggests.
“Infant mortality and neonatal mortality rates have continued to decrease when birth weight — and gestational age — specific analyses are done,” study researchers wrote. “The narrowing gap between infant mortality and neonatal mortality rates is due to the increased proportion of extremely low birth weight and preterm infants.”
Researchers analyzed data from the National Center for Health Statistics and linked birth and infant death cohort data files for all years available between 1983 and 2005 to determine effects of birth weight and gestational age subgroups to trends in infant mortality rates and neonatal mortality rates.
Researchers found an increase of low birth weight infants from 1.2% to 1.5% (P<.001) from 1983 to 2005. The amount of live birth infants weighing less than 500 g also increased from 0.12% to 0.18% during this period.
According to researchers, from 1983 to 1999 total infant mortality rate was declining significantly (P<.001), but from 2000 to 2005 there was no significant decrease (P=.28).
There also was an increase in low birth weight infant deaths from 42.9% to 54.8%, causing the recent insignificant decreases in infant mortality and neonatal mortality rates.
Researchers added that when excluding infants whose weight is less than 500 g, the adjusted infant mortality and neonatal mortality rates have steeper declining trends than when including those infants.
“The current study shows that infant mortality and neonatal mortality rates have continued to decrease during recent years in the United States when birth weight-specific analysis is done,” researchers wrote. “The increasing proportion of infants in the lower birth weight groups in preventing larger decreases in infant mortality and neonatal mortality rates. The extent to which the increased proportion of lower birth weight infants is due to reporting vs. actual increased births cannot be determined from our analysis.”
Disclosure: The researchers report no relevant financial disclosures.
Click Here to Manage Email Alerts