Female Age
This is a key consideration in evaluating fertility. Conception and healthy fetal development depend primarily on the quality of a woman's eggs, and egg production and quality in turn is largely dependent on a woman's age. One of the most frustrating aspects of older parenthood is the simple fact that egg quantity and quality declines with age. While a woman is born with about 2 million eggs, this number declines to about 300,000 at puberty. A woman will ovulate her healthiest eggs during her 20s and early 30s. By the mid 30s the remaining eggs are of lower quality, and by the early 40s only eggs with very low fertility potential are available for ovulation. As eggs age, they are more likely to have abnormal numbers of chromosomes, leading to failure of a fertilized egg to develop to the point of implanting in the uterus and to a higher likelihood of miscarriage. Age also may affect the production of the hormones estrogen and progesterone, which are essential to establishing and maintaining pregnancy.