Birth order linked to 150 health conditions in study of 10 million American siblings

Whether someone is the older or younger sibling may be linked to certain health outcomes later in life, according to a massive new study.

Analyzing medical data from 10 million U.S. siblings over two decades, researchers from the University of Chicago and Columbia University found links suggesting that birth order may be connected to specific long-term health risks.

Researchers examined 569 disease categories across families and among siblings, identifying 150 conditions that were significantly associated with birth order.