>> reporter: the researchers say conditions that cause a spike in insulin can starve a mother's tissues of oxygen, lowering the oxygen supply to their unborn child and potentially affecting its brain development. >> pretty normal. >> reporter: right now more than 60% of women of child bearing age in the u.s. are considered overweight or obese. >> if you are planning a pregnant si, you might think about losing weight and getting your exercise routine in order and making sure you're controlling your blood sugar. >> reporter: factors that could help the next generation's physical and mental health. michelle franzen, nbc news. well, the nicks return. the tigers claw the red sox in extra innings and the pirates don the -- your first look at sports is straight ahead. you're watching first look on m snchtsz nbc. [ barking ] i'm your dog,