Two Americans and a German won the Nobel Prize in medicine Monday for gene studies that help to explain birth defects and miscarriages.

They were chosen for discoveries about how genes control early embryonic development, said the medicine prize committee at Sweden's Karolinska Institute.

The winners are Edward B. Lewis, 77, at California Institute of Technology in Pasadena; Eric F. Wieschaus, 48, of Princeton University; and Christiane Nuesslein-Volhard, 52, at the Max-Planck Institute for Developmental Biology in Tuebingen, Germany.