As you age, the number of eggs and their integrity (function and normal chromosome number) gradually decrease. While it was previously believed women do not produce eggs throughout their lives, but are born with all the eggs they will ever have, research in the past 10 years has indicated this might not be true after all. Nevertheless, any later egg production will be minimal. Eggs will remain arrested at Stage I of cell division for up to 50 years, and division resumes prior to ovulation.
As you age, DNA errors occur more frequently because cell divisions are of lower fidelity, and this leads to abnormal chromosome number. Taken together, these events explain the age-related decline in reproductive capacity (e.g.lower rates of natural conception) and the poor results obtained with assisted reproduction technologies (ARTs). Women also experience an increased risk of pregnancy complications (perinatal morbidity and mortality, such as birth defects, diseases, or death that occur within a few weeks before or after birth) and of adverse outcomes for the children as they age.
Finally, female fertility reaches a natural limit and ceases entirely with menopause.