A full term baby is born after 37 to 40 weeks of pregnancy, and births before 37 weeks are termed as preterm or premature. There are many physical and mental complications to infant that come along premature births. Not only this, economic losses associated with such births are also remarkable. A new study is associating preterm births in the US to air pollution.

The research was conducted on the basis of data collected through the Environmental Protection Agency, the Centers for Disease Control and Prevention and the Institute of Medicine. According to the data, nearly 3% of the preterm births in the United States are caused due to intoxicated air. Accumulation of toxic chemicals in the blood can cause immune system stress which further weakens the placenta and shortens the amount of time the baby can remain in the womb.

Despite the fact that preterm birth rate has declined in the US from 12.8% in 2006 to 11.4% in 2013, the rate is high if compared with other developed nations. Premature births caused by air pollution were reported more in urban counties, mainly in Southern California and the Eastern US. There are almost 16,000 preterm births experienced each year and more than $4 billion annually is spent on care of such births linked to air pollution.

"Air pollution-associated preterm birth contributes direct medical costs in the first few years of life due to associated conditions, such as in the newborn intensive care unit, as well as lost economic productivity due to developmental disabilities and lost cognitive potential," said lead study author Dr. Leonardo Trasande, an environmental health researcher at New York University School of Medicine in New York City.

The problems faced by preterm infants in weeks after births are difficulty in breathing and digesting food. The babies can even face long term loss such as impaired vision, hearing, and cognitive skills as well as social and behavioral problems.