Researchers at Indiana University School of Medicine have reason to say "yes". The study, published in the April 2009 issue of the journal Acta Pædiatrica, is the first to report that birth defect rates in the United States were highest for women conceiving in the spring and summer.

The researchers studied more than 30 million births between 1996 and 2002 and discovered an increased number of birth defects seen in children of women whose last menstrual period occurred in April, May, June or July. This correlation was statistically significant for half of the 22 categories of birth defects reported in a Centers for Disease Control database from 1996 to 2002 - including spina bifida, cleft lip, clubfoot and Down's syndrome.

Another startling association found by the researchers was that elevated concentrations of agrochemicals and pesticides also occurred during these same months in the year.

"While our study didn't prove a cause and effect link, the fact that birth defects and pesticides in surface water peak during the same four months makes us suspect that the two are related," said Paul Winchester, M.D., Indiana University School of Medicine professor of clinical pediatrics, the first author of the study.

"Birth defects, which affect about 3 out of 100 newborns in the U.S., are one of the leading causes of infant death. What we are most excited about is that if our suspicions are right and pesticides are contributing to birth defect risk, we can reverse or modify the factors that are causing these lifelong and often very serious medical problems," said Dr. Winchester, a Riley Hospital for Children neonatalogist.

Birth defects are known to be associated with risk factors such as alcohol, smoking, diabetes or advanced age. However, the researchers found that even mothers who didn't report these risk factors had higher overall birth defect rates for babies conceived from April to July.

The study relies on findings by U.S. Geological Survey, the U.S. Environmental Protection Agency and other agencies on the seasonal variations in nitrates, atrazine and other pesticides in the surface water.

"These observations by Dr. Winchester are extremely important, as they raise the question for the first time regarding the potential adverse effect of these commonly used chemicals on pregnancy outcome – the health and well-being of our children," said James Lemons, M.D., Hugh McK. Landon Professor of Pediatrics at the IU School of Medicine. Dr. Lemons is director of the section of neonatal-perinatal medicine at Riley Hospital.

Source: http://newsinfo.iu.edu/