Louise Flick, a professor of epidemiology at Saint Louis University in Missouri, who was not involved in the study, said that infant mortality is considered a very sensitive indicator of the general population's health "in that it is exquisitely responsive to poverty, maternal education, housing quality and other factors." However, "it is a surprise to me that there would be that much of a fluctuation in the relatively short period of a presidential term," Flick told Live Science.
Still, the link "fits with a lot of other research about the social determinants of health, and particularly about the impact of the income gap between the richest and the poorest members of a society," said Flick, whose own research focuses maternal and child health.
However, she noted that it may not be the president's party itself that affects infant mortality, but rather, something changing in society that leads to the election of a given president and contributes to a change in infant morality. "There could be forces changing in the country, either in attitudes of the population or economic circumstances, that lead to both a decline in [infant mortality] and the ease with which a democratic president could be elected," Flick said.