According to a new paper published in Environmental Health Perspectives, high levels of air pollution might interfere with fetal development and can cause lower birth weights.

The study released in a scientific journal on Tuesday used data from the 2008 Olympics in Beijing. At that time, the Chinese government took aggressive measures to significantly reduce air pollution.

The study found that babies born during or shortly after the Olympics were heavier than those born at the same time of year in 2007 or 2009.

In 2008, the government restricted car and truck use, seeded clouds to create rain and temporarily shut down factories and construction sites. These measures dramatically improved Beijing's famously poor air quality.

It also reduced the levels of sulfur dioxide by 60% and levels of both carbon monoxide and nitrogen dioxide by over 40%. However, pollution returned to normal after government relaxed these restrictions after games.

For the study, the researchers focused on mothers who were in their eighth month of pregnancy during the Olympics. The eighth month of pregnancy was selected as it's a crucial period for fetal development.

Babies grow in size the most during the last stages of pregnancy. Then they compared those mothers to the ones who were pregnant at the same time in the years before and after the games.

After examining records of more than 83,000 Beijing births, the researchers found that the mothers pregnant during the Olympics delivered on average 23 grams heavier babies than the ones who were born during non-Olympic years.

Junfeng Zhang, a doctor with Duke Global Health Institute and a co-author of the study, said, "While Beijing's pollution is particularly noteworthy, many of the world's other cities face similar air quality problems. This study shows that pollution controls, even short-term ones can have positive public health benefits".