What are the monthly chances of conception?

The number and quality of the woman's egg have a significant impact on the rate of conception. A woman's prime reproductive years are in her 20s, claims the American Society for Reproductive Medicine. In the 30s, fertility gradually decreases, especially around age 35. A 30-year-old woman who is healthy and fertile has a 20% chance of becoming pregnant each month she attempts. Accordingly, 20 of every 100 fertile 30-year-old women who attempt conception in a single cycle will be successful; the remaining 80 will need to make another attempt. Less than five out of every 100 women are anticipated to be successful each month by the age of 40, when a woman's chance of success is less than five percent per cycle.