The luteal phase is the period from ovulation to the day before the onset of menstruation, which is called the luteal phase and normally lasts about 14 days. The luteal phase is when a woman produces the corpus luteum after ovulation. The corpus luteum secretes progesterone, which converts the proliferating endometrium into the secreting endometrium, making it easier for a fertilized egg to implant. If the fertilized egg does not settle, the endometrium will disintegrate and menstruation will come. Normally, a woman’s body temperature rises about 0.3°C during the luteal phase. If a woman’s basal body temperature is biphasic, it means that she is ovulating.