I have been charting my temperature during my last 2 cycles because we're trying to get pregnant. From what I've learned, the luteal phase (ovulation to period) should stay pretty consistant from cycle to cycle, and the follicular phase (period to ovulation) is the one that will change when stressed or ill, etc. My last luteal phase was 12 days and this month I went up to the mountains and the day I got there I spotted and the next day my period started and my temp dropped, making this luteal phase only 9 days! I also have an ovarian endometrioma cyst that I am going to have removed and I wondered if that could affect my luteal phase since it was shown by ultrasound that I ovulated on that side this month. Thanks in advance for your help and I will ask my doctor when I have my appointment in March.