Forty is not the new 30, at least in terms of reproduction. Although a woman may have reached an ideal time to have children at 40 in terms of work and relationships, the truth is that her fertility has declined over time and will not be the same as it was at the age of 30.
At the age of 35 a decline in female fertility begins, which becomes more pronounced from the age of 40 onwards. This is due to a deterioration in the quality and quantity of oocytes. Thus, the chances of conceiving naturally decrease with a woman's age. For this reason, many older women who wish to conceive turn to assisted reproduction techniques to fulfil their desire.