The study looked at the aftermath of the Three Mile Island accident in Pennsylvania, which caused two nuclear plants in Tennessee to be shuttered and their power to be replaced locally by coal generation.
After the energy switch, the weight of newborns fell by 5.4 per cent in Tennessee Valley counties that had the highest levels of air pollution from coal particles emitted by the replacement plants, the investigation found.
"Average birth weight declined approximately 134 grams (4.7 ounces) after the nuclear shutdown," said Edson Severnini, a researcher at Carnegie Mellon University in Pittsburgh, Pennsylvania. In the most affected places, "infant health may have deteriorated," he added.
The research, published in the peer-reviewed journal Nature Energy, touches on a debate about the risks of coal versus nuclear energy, triggered most recently by the 2011 Fukushima nuclear disaster In Japan.
More From This Section
Supporters of nuclear, while acknowledging concerns about accidents, say that the technology has a far better record for safety and public health than coal, which generates particles that are a respiratory hazard as well as climate-altering greenhouse gases.
Scientists estimate that in China and India alone, more than 200,000 people die prematurely each year due to coal pollution.
In contrast, supporters of coal say that pollution technology today is far better than four decades ago, and promote a vision of a "clean coal" with a far lower risk to the environment and health.
Severnini said the findings of his research call for reflection on the perceived benefits of shuttering nuclear plants.
"The shutdown of nuclear power plants in the United States and abroad might not generate as much net benefit as the public perceives," he suggested.