A better understanding of reproductive anatomy and physiology has led to newer methods of natural family planning, including the ovulation method and the symptothermal method. Studies have shown that 1 percent of couples who consistently and correctly use either of these methods conceives during one year of use. However, in the absence of standardized interpretation of study results, use-effectiveness data of these methods vary widely. The lactational amenorrhea method may be used in selected patients during the first six months postpartum, and its effectiveness in avoiding pregnancy is reported to be as high as 98 percent. Advocates of natural family planning promote these methods as inexpensive and safe ways to determine periods of peak fertility and point to the potential benefit of increased communication in a relationship.