For most women, age best predicts the chance of conception per month. On average it takes three to four months for a 25-year-old woman to conceive if everything else is normal and it takes twice this time for someone who is 35, and by the time you are 39 the time of conception will be 15 months.
After the age of 35 there is a significant drop in the chance of conception per month. However, despite of having normal periods and menstrual cycle, about 10 percent of women lose their fertility much sooner due to Follicle atresia and age effect on the spindle within the egg (the egg has a spindle on which the chromosomes align themselves). Not every woman is born with the same number of eggs or loses them at the same rate.
Since AMH is produced only in small ovarian follicles, blood levels of this substance have been used to measure the size of growing follicles in women. Therefore, AMH blood levels are thought to reflect the size of the remaining egg supply - or "ovarian reserve".
Whether you decide to wait or not, unfortunately women have to be aware of their biological clock unlike the male, whose age have almost no effect until he is well over 55. We are NOT saying to hurry and run to have a baby, but to know the facts when you do decide to bring your own little miracle into the world.