News Release

When Republicans control state legislatures, infant mortality is higher

The party that controls state legislatures is powerfully associated with fluctuations in infant mortality rates and racial disparities in infant health, scientists report in the American Journal of Preventive Medicine

Peer-Reviewed Publication


Ann Arbor, September 14, 2021 – Net of history, infant and postneonatal mortality rates are substantively higher under Republican-controlled state legislatures than under non-Republican–controlled ones, according to a new study in the American Journal of Preventive Medicine, published by Elsevier. Findings suggest that effects may be greater for Black infants than for White infants.

“These findings support the politics hypothesis that the social determinants of health are, at least in part, constructed by the power vested in governments,” said lead investigator Javier M. Rodriguez, PhD, Department of Politics & Government, Claremont Graduate University, Claremont, CA, USA.

Many social and health obligations depend on the decisions state representatives make. State legislatures are responsible for safety-net programs, the state’s minimum wage and many other public goods and services that influence the social determinants of health. The influence of state governments on population health has followed decentralization patterns since the 1970s, when states started to expand their independence from federal jurisdiction over welfare programs, including those directly affecting infant health, such as Medicaid.

The investigators examined how changes in the party composition of state legislatures, as well as in the upper and lower houses and governorships affected infant mortality rates, neonatal mortality rates and post-neonatal mortality rates from 1969 to 2014. They also analyzed annual state unemployment rates, average age of female individuals, birthrates and other sociodemographic data.

They found that, net of history, infant mortality is consistently higher under Republican-controlled state legislatures than non-Republican–controlled ones. Going from a non-Republican–controlled state Congress to a Republican-controlled one is associated with a 4.2% increase in infant mortality and an 8.1% increase in postneonatal mortality. Their findings show larger estimates for Black than for White infants, although the differences were not significant at conventional levels. Research has found that the introduction of Medicaid was associated with an 8% decline in non-White infant mortality between 1965 and 1980 (Goodman-Bacon, 2018). The annual increase in Black infant mortality under Republican legislatures found in this study is 5.9% — that is, equal to about 75% the magnitude of the 15-year benefit attributed to the introduction of Medicaid. 

Aside from party control of legislatures, the investigators found no clear evidence that Republican governors impact infant mortality rates. The investigators suggest that this may reflect variability in the balance of power between legislative and executive branches across the states. Some governors’ health policy positions seem to be more synchronized with state-level culture than with national party ideological stances. For example, some Republican governors who are not highly conservative in the conventional sense may be more aligned with a Democratic legislature on healthcare issues.

The investigators caution that the study may not account for unobserved differences across states that may change at the same time as the party control change of state legislatures, and other mechanisms not included in the study may connect Republican administrations and increases in infant mortality rates.

Nevertheless, the findings emphasize that the power that political institutions and governments have on writing and executing the policies and programs that shape the social determinants of health, including those shaping infant health.

“Unfortunately, in a drastically polarized political environment, it is often difficult for Americans to notice the underlying mechanisms that distribute the production of illness and human suffering that ultimately decide who lives and who dies of preventable reasons,” commented Dr. Rodriquez. “As political decisions are a matter of life and death, the parties, politicians and policies that Americans support should be evidence-based and incorruptible. A deep understanding of political processes and institutions at the state level is necessary for improving overall population health and promoting health equity.”


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