" mothers suffered from major nausea and vomiting during pregnancy. When the children reached school age, 21 percent scored 130 or more points on a standard IQ test, a level considered gifted. If their mothers had no morning sickness, only 7 percent of kids did that well. The researchers have a theory—still to be proven—about why. Two hormones that stimulate a woman to vomit may also act like neural fertilizer for the developing brain. "

― John Medina , Brain Rules for Baby: How to Raise a Smart and Happy Child from Zero to Five