– A woman is born with a limited number of eggs.
– The number and quality of eggs begin to decline after the age of 32 to 35.
– It is recommended that a woman plan her reproduction before turning 40.
– Egg freezing is an alternative.
When a woman is born, she has approximately two million eggs stored in her ovaries. From that point on, she does not produce new eggs; on the contrary, she begins to lose them at an accelerated rate. By puberty, this number is reduced to only 400,000, and they are completely depleted at around age 50.
Over time, in addition to the decrease in number, the quality of the eggs that remain in storage deteriorates. Deteriorated eggs may fail to fertilize, resulting in no pregnancy occurring in the month that the egg is released.
Deteriorated eggs can also be fertilized, but they may result in a pregnancy that is quickly lost through miscarriage or in a baby with abnormalities. The most common abnormalities associated with a woman’s age are: trisomy 21 (Down syndrome), trisomy 18 (Edwards syndrome), and trisomy 13 (Patau syndrome).
For example, in 20-year-old women, one baby is born with Down syndrome for every 2,000 births, but in 35-year-old women, it occurs in one out of every 450; and at 45 years old, in one out of every 20. The most common anomalies (for example, Down syndrome) can be detected through a blood test of the mother at two months of pregnancy.
A woman’s fertility, therefore, is at its peak efficiency between the ages of 18 and 30. From then on, fertility begins to decline slowly until age 35 and declines rapidly after that, with the probability of pregnancy being very low after age 43, although it is not completely impossible.
Thus, a woman has a biological imperative to define her reproductive life at an early age, often at the expense of other life projects. A medical recommendation in this regard is that a woman should try to make her reproductive decisions before age 35. Unfortunately, this is not always possible or desirable.
Reproductive medical technology can offer an alternative by allowing “young” eggs to be frozen, which remain preserved for use several years later, thereby maintaining high fertility and a low risk of abnormalities for the baby.
