Over the last decade, delaying childbearing until later in life has been a common choice amongst couples. A variety of factors may contribute to a couple’s decision to delay starting a family such as career choices, economic reasons and the misconception that fertility doesn’t diminish with age. The decision to delay pregnancy is accompanied by a reduced chance to successfully conceive and/or deliver a healthy baby.

Effect of Age on Women

For women, fertility peaks in the early 20s and declines after age 35. The greatest impact on female fertility is a decrease in the quantity and quality of their eggs. As a woman ages, her eggs are more likely to have chromosomal abnormalities, and the risk of an abnormal embryo increases. If pregnancy does occur, embryos are less likely to develop, and there is a higher incidence of miscarriage.

A woman produces an entire lifetime supply of eggs very early in her own development. This entire process is completed prior to birth with approximately two million eggs available at birth. The eggs are immediately surrounded by a special layer of supporting cells and enter a resting state where they will remain until puberty. No new eggs are produced.

As the eggs leave the resting state and resume development, there is a steady decline in the number of eggs that remain in reserve within the ovaries. The number of eggs declines to about 300,000 by the time a woman enters puberty. The gradual decline continues throughout her reproductive life. Many eggs start the developmental process every month, but fewer of these will ripen. Eventually a woman will exhaust her supply of eggs, cease having spontaneous menstrual cycles and become menopausal. Many changes occur in the premenopausal years including a change in the length of the menstrual cycle or heaviness of periods.

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