Study: Conceiving in Summer Lowers Baby's Future Test Scores

Would-be parents who want to ensure their kids will have a leg up in school might want to consider the time of year they conceive. A group of researchers have found that the time of year a child is conceived may affect his or her future academic performance.

A study by an Indiana University School of Medicine pediatrician found that children conceived between June and August recorded lower ISTEP scores than children conceived the rest of the year.

Researchers found no definite reason for the difference, but one possible culprit could be the pesticides and nitrates used on crops and lawns in the warmer months. They could have an effect on the earliest development of fetal brains.

"The best conclusion that we can draw from this is that the hypothesis that there is no environmental phenomenon affecting ISTEP scores -- that hypothesis is wrong," said Dr. Paul Winchester, the IUSM professor of clinical pediatrics who did the research.

Winchester, also director of newborn intensive care services at St. Francis Hospital, linked the ISTEP scores of 1,667,391 students in third through 10th grades to their birthdates, working back 39 weeks to determine when they were conceived.

Previous work found that children conceived between April and July had a higher rate of birth defects. Winchester wondered whether contaminants might also affect cognitive ability.

Such contaminants may act as endocrine disrupters, lowering a mother's thyroid levels. Low maternal thyroid levels are associated with lower cognitive scores, Winchester said.

If the pesticides had no effect, he would have seen the same scores no matter when a child was conceived, he said.

Instead, he found a small but statistically significant difference in scores. More studies are needed to prove a definitive connection between pesticides and academic achievement, he said.

"We don't want to cause a panic, but . . . we need to be paying more attention to this," Winchester said.