A to Z weight-loss study. Pre-menopausal women age 25 to 50 and with at least 20 pounds to lose are needed for a weight-loss study comparing the Atkins, LEARN, Ornish and Zone programs. Eligible participants must not be pregnant, nursing or planning to become pregnant and must be willing to accept random assignment to one of the four programs for 12 months. The Stanford Prevention Research Center study provides free eight-week classes, body composition tests, cholesterol tests, monitoring of weight and other health measures. For details on the A to Z study, call 725-5018 (press 4) or visit http://nutrition.stanford.edu.

Ob/Gyn preimplantation study. Participants are needed for a study to determine whether preimplantation genetic diagnosis, or PGD, lowers miscarriage rates and improves pregnancy outcomes. PGD, which occurs before pregnancy, is an alternative to prenatal diagnosis. Eligible participants for the Department of Obstetrics and Gynecology study include women ages 38 to 43 needing to undergo in vitro fertilization and women ages 18 to 43 with more than one miscarriage. For details call 498-7911.