How Long Am I Fertile?

My Fertile Days

It is only during the most fertile days of your menstrual cycle that the optimal conditions for getting pregnant are satisfied. This fertile period is therefore the best time of the month to have baby-making intercourse.

The most fertile days of the menstrual cycle usually include the day of ovulation and the days preceding and following ovulation. The egg released during ovulation only has a lifetime of up to 48 hours and the sperm survives in the vaginal environment for an average of 60 to 120 hours. During your fertile period, the vaginal environment becomes more welcoming and friendly to sperm. Cervical mucus becomes less acidic and more elastic and the cervix moves from a low, firm, dry and closed position to being soft, high and open. All these changes facilitate the passage of sperm to the uterus and the Fallopian tubes, where fertilisation of the released egg usually occurs.

Given that the day of ovulation is so important to understanding your fertility, it will come as no surprise that many women monitor their bodies for signs of ovulation. What might come as a surprise however, is a recent study by Sievert et al. that demonstrated that although approximately 50% of women think they know when they ovulate, only about 15% actually do know!

Sperm needs to be present at the moment of ovulation or just after it has occured. If sexual intercourse occurs too early, the sperm will either never reach the uterus and Fallopian tubes, or will not survive long enough in the vaginal environment to fertilise the egg. 

It is believed that the quality of the egg released during ovulation also affects your chances of getting pregnant. Egg quality refers to the ability of the egg to be fertilised by a sperm. Certain characteristics are required for the egg to successfully develop into an embryo, and these include:

• The proper chromosomes (the structures containing genetic information in the form of DNA)
• The egg's ability to combine with sperm
• The presence of energy reserves to split after fertilisation

Age is an important factor in terms of both the quantity and quality of the eggs. Egg quality tends to decline with age, as does the remaining number of eggs which can be released during ovulation. This explains why fertility levels usually decline with age. This does not mean, however, that eggs always decline in quality past a certain age. Some women have good quality eggs until the end of their reproductive lives while others have poor quality eggs at a younger age. Nevertheless, it is believed that egg quality begins to decline when women reach their late 30s and continues to decline throughout the 40s.