Infant mortality rates recently increased for blacks in the United States, whereas the rates in whites continued to decline, a new study shows.

The difference in mortality rate between black infants and white infants, per 1000 births, fell from 8.6 to 6.6 from 2005 to 2012, and then rose to 6.9 in 2015, the authors say.

Corinne A. Riddell, PhD, from McGill University, Montreal, Quebec, Canada, and colleagues, published their findings online July 3 in a research letter in JAMA Pediatrics.

"The sustained progress in reducing infant mortality among black infants since 2005 has stalled in the past few years," they write. "This has led to increases in the absolute inequality in infant mortality between black and white infants during the past 3 years."

According to the Centers for Disease Control and Prevention, the infant mortality rate in the United States dropped 15% from 2005 to 2014.

The researchers therefore aimed to determine whether both black and white infants benefitted equally from the decline.

In their cross-sectional study, the researchers analyzed data from the US National Vital Statistics System from 2005 to 2015. They examined trends in overall and cause-specific infant mortality rates between non-Hispanic black and white infants, as infant mortality is widely used as a measure of population health.

The infant mortality rate for black infants fell from 14.3 to 11.6 per 1000 births from 2005 to 2012, then plateaued until 2014, and then rose from 11.4 to 11.7 per 1000 births from 2014 to 2015.

In contrast, the mortality rate for white infants decreased from 5.7 to 4.8 per 1000 births during the 10-year period.

The researchers also determined rates for the top four causes of infant death, as well as for an additional category comprising all other causes.

The top cause of death among black infants is short gestation and low birthweight, with blacks experiencing almost four times as many deaths as whites in this category. Although deaths from short gestation and low birthweight decreased for black infants between 2005 and 2011, they more recently plateaued. The mortality rate in this category for black infants vs white infants was 309.2 vs 78.2 deaths per 100,000 births in 2005 compared with 263.4 vs 74.5 in 2012 and 256.9 vs 69.7 in 2015.

For the three other top causes of death (congenital malformations, sudden infant death syndrome, and maternal complications), the mortality rates decreased among both black and white infants from 2005 to 2015.

However, deaths related to both sudden infant death syndrome and congenital malformations increased for black infants from 2014 to 2015, the authors add.

The data showed that progress has also recently stalled with respect to all other causes of infant death. The mortality rate in this category for black infants vs white infants was 721.9 vs 282.8 deaths per 100,000 births in 2005 compared with 571.6 vs 235.6 in 2012, and 593.0 vs 236.7 in 2015.

Dr Riddell and colleagues thus stress that no one specific cause is responsible for the recent rise in black infant deaths.

Highlighting data showing that the preterm birth rate is nearly 50% higher for black infants compared with white infants, the researchers therefore conclude that strategies to further lower the preterm birth rate among black infants may be "the most promising option for reducing black infant mortality and the absolute inequality between black and white infants."

This study was supported by an award from the Fonds de la Recherche en Santé du Québec and a Canada Research Chair in Health Disparities grant. The authors have disclosed no relevant financial relationships.

JAMA Pediatr. Published online July 3, 2017. Abstract

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