(NewsTarget) The use of pesticides and nitrate-containing fertilizers is almost certainly responsible for rising rates of premature birth in the United States, according to research presented at the Pediatric Academic Societies' annual meeting in Toronto, Canada.

The Pediatric Academic Society is a gathering of the American Pediatric Society, the Society for Pediatric Research, the Ambulatory Pediatric Association, and the American Academy of Pediatrics.

The research, performed by Paul Winchester, a medical doctor and a professor of clinical pediatrics at the Indiana University School of Medicine, showed that premature births were highest in the months of April through July -- May and June in particular -- and lowest in August and September. This correlated precisely with the seasonal variation in surface water concentrations of nitrates and pesticides. This correlation was independent of the mother's age, education, marital status, age, substance use and area of residence (rural, urban or suburban). The study population consisted of 27 million live births between 1996 and 2002.

"Preterm births in the United States vary month to month in a recurrent and seasonal manner. Pesticides and nitrates similarly vary seasonally in surface water throughout the U.S. Nitrates and pesticides can disrupt endocrine hormones and nitric oxide pathways in the developing fetus," Winchester said.

Premature babies are those born before the 37th week of pregnancy. Due to underdeveloped organs and low body weight, they suffer serious health problems and risks, and must often be kept alive on expensive machinery until their bodies can more fully develop. The occurrence of premature birth in the United States has risen by 30 percent since record keeping began in 1981.

"A growing body of evidence suggests that the consequence of prenatal exposure to pesticides and nitrates as well as to other environmental contaminants is detrimental to many outcomes of pregnancy. As a neonatologist, I am seeing a growing number of birth defects, and preterm births, and I think we need to face up to environmental causes," Winchester said.