Researchers found that children conceived in the summer months (May to August) posted lower scores on math and language tests compared to children conceived during the other months.

This study was conducted by the Indiana University School of Medicine on test scores of 1,667,391 students in grades 3 - 10. The correlation was held regardless of race, gender, and grade level.

Apparently, the evidence of the correlation of test scores and date of conception, points to the high level of pesticides and nitrates in surface water during the summer months. Exposure to these chemicals by the mother may affect the development of the fetal brain. Although no findings support that exposure to such elements contribute to lower test scores, past research linked exposure to such elements to hypothyroidism. And hypothyroidism in pregnancy is linked to lower intelligence test scores in offspring.

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