It may be time to rethink traditional advice to wait at least three months after a miscarriage before trying to conceive again, according to a new study published online Monday in Obstetrics & Gynecology. Couples who attempted within a three-month window after losing a pregnancy had a 53 percent chance of a later live birth in the six-month study interval, compared with a 36 percent chance for couples who waited longer, the study found.