Preterm infant mortality in the U.S. has dropped, but remains high for Black infants

The mortality rate of preterm infants has dropped significantly over the past 26 years in the United States, according to research findings reported in JAMA Pediatrics today. But that good overall news obscures persistent differences that follow racial, ethnic and socioeconomic lines.

The preterm infant mortality rate decreased from 33.71 per 1,000 preterm births in 1995-1997 to 23.32 per 1,000 preterm birth in 2018-2020, according to Tim Venkatesan, M.A. (Cantab), of the Department of Population, Policy and Practice at the University of Great Ormond Street Institute of Child Health of University College London in the United Kingdom, and colleagues. The improvement was greatest among those born very (28-31 weeks) and extremely (22-27 weeks) premature, they found, and was especially pronounced in those born between 23 and 27 weeks of gestation.

They noted that the overall trend in the U.S. is consistent with trends in other high-income countries and pointed to greater use — and the timing of that use — of antenatal steroids, exogenous surfactants and other aspects of respiratory care. Antibiotics, nutrition and controlling the body temperature of premature infants are also factors, they said.

When Venkatesan and his colleagues dug into racial and other differences in preterm infant mortality they also identified some encouraging trends. For Black infants, the preterm mortality rate fell from 44.51 per 1,000 premature term births in 1995-1997 to 31.09 per 1,000 premature births in 2018-2020. For Hispanic infants, the drop was from 27.34 per 1,000 premature births in 1995-1997 to 20.13 in 2018-2020 and for white infants, it was 31.59 per 1,000 premature births to 21.81.

The rate of decrease was steeper among Black infants, Venkatesan and his colleagues pointed out.

Still, as the researchers emphasized, Black infants remain 1.4 times more likely to die from prematurity than White infants and, furthermore, Black infants are 1.5 to 2 times more likely to be born prematurely than White infants.

“It is thought this difference is partially attributed to a higher proportion of Black infants being born at the extremes of prematurity,” they wrote in the discussion section of the paper, adding, though, that among infants born extremely prematurely that they found that mortality rates were comparable between racial groups with a slight survival advantage for Black and Hispanic infants.

Venkatesan and his co-authors also looked at socioeconomic status. Their results suggest the value of antenatal care; infants of mothers who received inadequate antenatal care had the highest preterm mortality rate. They also found associations between higher preterm mortality rates among infants whose mother smoked, were less educated or lacked private health insurance. However, among infants born extremely prematurely, the mortality rates were similar between those whose mothers were covered by private and those whose mothers were covered by government insurance, presumably Medicaid,

Venkatesan and his colleagues used data from the federal government’s National Center for Health Statistics to conduct their study. Annual figures are published routinely, but they said that trends in infant mortality by race and ethnicity and by socioeconomic status have not been reported until their findings were published by JAMA Pediatrics. The data they used included just under 104 million infants born from 1995 through 2020, of whom 12.3 million, or 11.8%, were born prematurely (22 weeks to 36 weeks). Of the premature infants, 438,000, or approximately 3.5%, died within the first year of life, they said.