What is the difference between a fertility window and ovulation day, and how does identification of each affect my ability to conceive?
Your ovulation day is defined as the day that the egg is released from the ovaries and makes its way to the uterus. Your probability of pregnancy on this day is about 5% according to an article by Dunson et.al in Statistics in Medicine (2001). LH test kits identify ovulation day for you. See chart below for day specific probabilities of pregnancy through out your fertile window.
The Fertility Window is the 6-day time period during your monthly menstrual cycle in during which sexual intercourse can lead to a conception. That is the 4 days before ovulation, ovulation day and the day after ovulation. In studies that were conducted at university based hospitals, it has been shown that the probability of conception is highest on the 4 days before ovulation, as sperm can remain alive inside a woman’s body for at least 5 days4. In fact, in some rare circumstances they may even stay alive for as long as 6 or 7 days.
Through the identification of the Fertility Window, you have defined a maximal period of time available to you whereby you and your partner can plan multiple attempts (many fertility experts recommend intercourse every other day after OV-Watch® has indicated fertile day one to maximize the quantity of sperm cells being delivered to the uterus) to conceive during the cycle. In this way, your cumulative probability of a successful conception can be maximized. By having intercourse during the 4 days before pregnancy, you can double your chances of pregnancy.