In Canada, half of babies born today have a mother who is over 30 years of age, which is twice as old as mothers were in 1975. Although this reality reflects a profound change in our society, keep in mind that it’s more difficult for a couple to conceive as the mother gets older.
The effects of age on female fertility
In contrast to men, who constantly renew their supply of sperm, the female eggs are limited in number. When she is born, a young girl has 1 to 2 million eggs. Over the years, this number gradually drops. The ovarian reserve of a 30-year-old woman only contains 12% of the eggs she started out with and only 3% by age 40. In addition to reducing the number of eggs produced, age also diminishes the quality of eggs.
The effects of age on male fertility
The effects of age are also present in men, but to a lesser degree. After age 30, the level of testosterone, which is necessary for producing sperm, decreases by about 1% a year. The quality of sperm also declines. The sperm of men 40 and over can contain 3 times as many mutations in their DNA as those of men aged 20.