Rob Stein

Results from two sets of experiments provide encouragement to researchers working on "chimera" embryos that may someday be used to grow organs for transplantation into people.

In its update of ethics rules aimed at protecting patients, the Obama administration decided against a provision that scientists said would hinder research. Consumer advocates aren't happy.

Research from Denmark suggests about one-third of lumps detected by routine mammograms would never have become dangerous. That puts women at risk of needless surgery, radiation or chemotherapy.

The Zika virus emerged as a global threat to pregnant women and their developing babies in the last year. What have we learned in 2016 and what can we expect from Zika?

Seeing someone close to you experience racial discrimination may have more of an effect on health than experiencing that discrimination yourself, a study finds.

Women who were infected with Zika virus while abroad and then came to the U.S. had complications about 6 percent of the time, a study finds. First-trimester exposure was linked to more birth defects.

A powerful genetic engineering technique holds promise for wiping out diseases and improving agriculture. But the species-altering approach stirs anxiety about unintended consequences.

Overall, U.S. life expectancy dipped in 2015 — the first drop since 1993. That's because the death rate went up between 2014 and 2015, driven by an increase in mortality among people younger than 65.

One-quarter of mothers with the lowest incomes told researchers they'd administered physical discipline to a kindergarten-age child in the past week. Overall, though, physical discipline has declined.

A large study alleviates concerns that Celebrex boosts the risk for heart attacks and strokes as much as Vioxx. But the findings raise some concerns about prescription doses of ibuprofen and naproxen.

A proposed change in work rules would let first-year residents care for patients for as many as 28 hours straight, scrapping a 16-hour limit. Supporters say longer shifts would improve patient safety.

Findings provide new evidence pushing back school start times, to let adolescents sleep and wake up when it's more natural, researchers say. It's going to bed late that creates problems.

An analysis of global demographics indicates the maximum human life span may have peaked at around 115 years. That's despite medical advances and the occasional person who lives a few years longer.

The Nobel Prize in Physiology or Medicine goes to a Japanese scientist who explained that cells have their own versions of recycling plants, how they work, and the role of this process in diseases.

Men who may have Zika should wait at least six months before having unprotected sex with partners trying to conceive, regardless of whether the men ever developed any symptoms, the CDC now says.

There's plenty of vaccine available this year, and the sooner people get vaccinated the better, federal health officials say. A recent drop in vaccination, especially among the elderly, concerns them.

The New York-based doctor has sparked praise and criticism by going to Mexico and using DNA from three adults to create a child for a couple from Jordan who lost two children to a genetic disorder.

A scientist in Sweden has started experiments on healthy human embryos in which DNA is altered. The aim is to determine the causes of infertility. It's the first known use of so-called "gene-editing" tools on healthy human embryos, and critics say it could potentially lead society down a very dangerous path.

A Swedish biologist wants to change the genes of healthy human embryos to find ways to treat infertility and other diseases. The experiments intensify ethical questions about genetic engineering.

Clinics are using stem cells to treat problems ranging from arthritis and torn tendons to paralysis and stroke. But researchers say there's no evidence that the treatments work or are safe.