Academic journal article The Science Teacher

Conception Time and Birth Defects

Academic journal article The Science Teacher

Conception Time and Birth Defects

Article excerpt

A study published in the medical journal Acta Paediatrica 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 also found that this period of increased risk correlated with increased levels of pesticides in surface water across the United States.

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Studying all 30.1 million births that occurred in the United States between 1996 and 2002, the researchers found a strong association between the increased number of birth defects in children of women whose last menstrual period occurred in April, May, June, or July and elevated levels of nitrates, atrazine, and other pesticides in surface water during the same months. While many of these chemicals--including the herbicide atrazine, which is banned in European countries but permitted in the United States--are suspected to be harmful to the developing embryo, this is the first study to link their increased seasonal concentration in surface water with the peak in birth defects in infants conceived in the same months.

The correlation between the month of last menstrual period and higher rates of birth defects 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. "Elevated concentrations of pesticides and other agrochemicals in surface water during April through July coincided with a significantly higher risk of birth defects in live births conceived by women whose last menstrual period began in the same months," says Paul Winchester, Indiana University School of Medicine professor of clinical pediatrics, the first author of the study. …

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