The birth of a sibling by first grade appears to lower a child's risk of obesity, according to a new study.
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Younger siblings can be annoying. Trust me—I had one.

They take your stuff without asking, they won't stay out of your room, they bother you when friends are over, and—worst of all— they just love to tattletale.

But, it turns out, having a little brother or sister may be good for your health.

According to a new study at the University of Michigan, the birth of a younger sib may lower a child's risk of becoming obese, especially if the older child is between 2 and 4 years old.

The study analyzed data from 697 children across the U.S. and found having a baby bro or sis was linked to healthier BMIs from the time the siblings are born until the older kid reaches first grade. Kids who didn't have youngers siblings by first grade were nearly three times more likely to be obese by first grade.


One possible explanation, the study authors said, could be that parents may change the way they feed their child once a new sibling is born. And since kids start to develop long-lasting eating habits around age 3, these changes can have a significant impact.

Another explanation, they said, may be that the older children assume a caregiver role when a younger sib is born, which means engaging in more active play and less sedentary time in front of screens, all of which contributes to healthier BMIs.

Pretty interesting stuff. And according to senior author Julie Lumeng, M.D., further studies are needed to determine how having a sibling may impact even subtle changes like mealtime behaviors and physical activity.

"Childhood obesity rates continue to be a great cause of concern," she explained. "Better understanding the potential connection between a sibling and weight may help health providers and families create new strategies for helping children grow up healthy."

Hollee Actman Becker is a freelance writer, blogger, and a mom. Check out her website for more, and follow her on Twitter at @holleewoodworld.