Ovulation takes place, on average, about two weeks before your period, though it can vary from 10-16 days before the onset of menstruation depending on the length of your luteal phase. During an average 28 day cycle, ovulation is usually expected to take place between cycle days 13-15. Based on this guideline, many women are taught to expect ovulation around day 14 of their menstrual cycle. Many women, however, do not have average cycles and even those who usually do may see irregularities from time to time.
I've read somewhere that cycles over 35 days are classed as an anovulatory cycle, I don't know if this is true!
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