New York, Jan 26 (IANS): Light pollution, based on a direct measure of skyglow, could increase the likelihood of preterm birth, a new study suggests.

The study, published in the Southern Economic Journal, examined the fetal health impact of light pollution based on a direct measure of skyglow -- an important aspect of light pollution.

Using an empirical regularity discovered in physics called Walker's Law, the team found evidence of reduced birth weight, shortened gestational length and preterm births.

"While greater use of artificial light at night (ALAN) is often associated with greater economic prosperity, our study highlights an often neglected health benefit of 'darkness'," said researcher Muzhe Yang from the Lehigh University in the US.

Specifically, the likelihood of a preterm birth could increase by approximately 1.48 per cent points (or 12.9 per cent) as a result of increased nighttime brightness, according to the researchers.

Nighttime brightness is characterised by being able to see only one-fourth to one-third of the stars that are visible in the natural unpolluted night sky.

One possible biological mechanism underlying the findings, based on the existing literature, is light-pollution-induced circadian rhythm disruption, Yang said.

While essential to a modern society, ALAN can disrupt a human body's circadian rhythm and therefore become a "pollutant". The societal benefits of ALAN, for example, through increased economic activity, may be offset by ALAN's negative externalities such as adverse health effects, the authors said.

The contribution of ALAN to the alteration of natural nocturnal lighting levels is often referred to as light pollution. Light pollution is considered a worldwide ongoing problem.