Researchers at the NIH pooled data from 16 human studies of blood substitutes conducted on 3,700 patients.

They found those given hemoglobin-based blood substitutes had a nearly three times higher risk for heart attack and a 30 percent increased risk for death.

Researchers speculate the hemoglobin may lead to narrow blood vessels, but more studies are needed.

Working parents are familiar with the increased costs of daycare, an expense that may come with an unexpected benefit.

A new study finds children who attend daycare, or regular play groups, have about a 30 percent lower risk of developing the most common type of childhood leukemia.

Researchers think exposure to common infections early in life--in this case, from other kids in daycare--could explain the apparent protective effect.