Your "fertile window" or "fertility window"  consists of the 6 fertile days of your menstrual cycle which are the days when intercourse can result in pregnancy: the ovulation day and the 5 days before. Those are the days a couple can get pregnant from having unprotected intercourse because the egg usually survives for about 12-24 hours after ovulation and sperm can survive up to 5 days. 

Recent data show that ovulation could happen on several days of your cycle, even with a regular period, and ovulation does not always happen on the same day each month. The range of your fertile day coverage as compared to the fertile or fertility window is potentially longer because they include all days during your menstrual cycle when you have the ability to become pregnant and takes into consideration a more flexible time period for ovulation.  The fertile days coverage is longer than the fertility window because ovulation does not always happen on the same day in each menstrual cycle but within a range of days. By calculating and identifying additional fertile days, not just the fertility window, we can provide couples with more flexibility to plan intercourse and more opportunities to conceive.