British researchers analyzed data on nearly 20,000 British children involved in an ongoing national study. These kids took verbal numbers and reasoning tests at ages five and seven .

They found children scored slightly lower if their mother was overweight going into pregnancy. Exactly what difference these test scores make in real life is unclear

The findings reported online in the journal "Pediatrics" do not prove a mother's extra pounds are the reason for the decreased scores, and experts not involved in the study say it's too soon to suggest mothers-to-be lose weight for the sake of their child's mental abilities. However, the results do add to research which associates kids born to heavier moms with lower IQ scores.