In Brief

WORK ETHIC College students who hold part-time jobs perform better academically than those who either work full time or don't work at all, according to a study by Upromise, a Massachusetts administrator of college-savings plans. The study suggests that working 10 hours a week or less more frequently cuts into nonproductive activities like watching TV than keeps students from their homework. Full-timers, though, are more likely to drop out.

STRESSED OUT Anxiety during pregnancy can double the risk of having a hyperactive child, possibly owing to exposure to the stress hormone cortisol, say researchers at London's Imperial College. Children's behavior is usually attributed to genes or parenting, the researchers say, but this study suggests there is a chemical component as well.

WALKER WATCH The 3 million walkers that American parents buy for their infants each year may do more harm than good, according to the American Academy of Pediatrics, which has recommended banning their manufacture and sale. There is no evidence that the devices help infants learn to walk independently; on the contrary, doctors say, they can delay normal motor development and cause serious injury and even death. In 1999, 8,800 children under age 15 months were treated in U.S. emergency rooms for injuries associated with walkers.