Season of conception tied to school performance

The time of year a womanconceivesmay influence the future academic performance of her child, according to research reported this week at the Pediatric Academic Societies' annual meeting.

When researchers linked standardized test scores of 1,667,391 Indiana students in grades 3 through 10 with the month in which each student had been conceived, they found that children conceived May through August scored significantly lower on math and language tests than children conceived during other months of the year.

The correlation between test scores and conception season held regardless of race, gender, and grade level.

Why might this be? According to Dr. Paul Winchester of Indiana University School of Medicine who led the study, the evidence points to environmental pesticides, used most often in the summer months, as a possible player.

The lower test scores correlated with higher levels of pesticides and nitrates in the surface water (nearby streams and other bodies of water) during that same time period, he told Reuters Health.

"Exposure to pesticides and nitrates can alter the hormonal milieu of the pregnant mother and the developing fetal brain," Winchester explained in a statement. For example, past research has linked exposure to pesticides and nitrates to low thyroid hormone levels ("hypothyroidism") in pregnant women and hypothyroidism in pregnancy has been tied to lower intelligence test scores in offspring.

While the current findings do not prove that pesticides and nitrates contribute to lower test scores, "they strongly support such a hypothesis," Winchester said.

"A priori there should be no reasons particularly why the month of conception should change your (test) scores," he added in an interview, "and yet from our chain of evidence our hypothesis was that if pesticides do alter the friendly environment of the developing fetus than that might be reflected in lower scores. And unfortunately that's what we found."

"There is something going on" and it needs to be studied further, Winchester concluded.

在本周舉行的"兒科學術協會年會"上，一項研究報告稱，母親懷孕的月份可能會影響孩子以后的學業成績。

研究人員對印地安那州1,667,391名3到10年級學生的統一考試成績和他們的受孕月份進行了相關分析。結果發現，與其它月份受孕的孩子相比，5月至8月受孕的孩子的數學和語言成績要低得多。

考試成績與受孕季節這一相互關系不受種族、性別和年級的影響。

該如何解釋這一結論？本研究的帶頭人、印第安納大學醫學院的保羅·溫徹斯特博士說，罪魁禍首有可能是空氣中的殺蟲劑，這些殺蟲劑在夏季使用得比較多。

他在接受路透社健康部的采訪時說，考試低分與地表水（附近的小溪和其它水體）中含量過高的殺蟲劑和硝酸鹽有關。

溫徹斯特解釋說，"接觸殺蟲劑和硝酸鹽會使孕婦體內的荷爾蒙環境發生改變，從而影響胎兒的大腦發育。"比如，以往的研究發現，孕婦體內甲狀腺激素含量低（甲狀腺機能減退）與接觸殺蟲劑和硝酸鹽有關，而懷孕期間甲狀腺機能減退又與孩子智商低有關。

盡管目前的研究不能證明殺蟲劑和硝酸鹽導致考試低分，但是，溫徹斯特說，"它們為這一假設提供了有力的支持。"

他在采訪中補充道，"我們是這樣推理的，既然沒有特別的原因來解釋受孕的月份影響考試成績這件事，那么根據一系列的證據，我們假設如果殺蟲劑確實影響胎兒成長的良好環境，那么這種影響也許會導致考試低分。不幸的是，這正是我們通過研究發現的。"

溫徹斯特最后總結到，"這其中還有一些影響因素"有待進一步的研究。

Vocabulary:
conceive: To become pregnant（懷孕）
hypothyroidism: 甲狀腺機能減退