There's an old adage that pregnant women are eating for two.
But if they'd been eating for two long before getting pregnant, that means their baby could suffer diseases associated with old age earlier in their lives - and it might even shorten their lifespan.
Belgian researchers say it has to do with something called telomeres, which are little bits on the ends of your chromosomes, like the plastic sheaths you find at the ends of shoelaces. They affect how your body makes new cells as it constantly rebuilds itself over the years.
The scientists examined 743 mothers, between 17 and 44 years of age.
They found that the higher mother's body mass index (BMI) was, the shorter their baby's telomeres were. For every one point higher, it added from one to 1.6 years to the newborn's biological age.
By that measure, if a man's mother had been chronically overweight leading up to the pregnancy, by the time his biological age reaches 45, he would then, physically speaking, be about 53.
That could mean earlier onset of age-related illnesses later in life, such as heart disease, Type 2 diabetes, and increased mortality.
That's a big concern in first-world societies like ours, where about 30 percent of women of reproductive age are overweight.
The scientists say they need more information about how the father's BMI plays a role here but it's known that when we achieve a healthy weight, that leads to a healthier life.
And now, it seems our weight could be a huge factor in our kids' lives, too.