**2.3. Fertility in older mothers' children**

Although most causes of infertility are not genetic, it has been observed in a US population study that daughters from mothers older than 40 years are more likely to remain childless in their lifetime [4]. However, it is difficult to discern whether this is a "learnt" pattern or a true "inherited" infertility trait. In the same population, daughters from "old" mothers were at double risk for delivering twins than daughters from "young" mothers (OR = 2.1, 95% CI: 0.8–5.4), although this difference was not statistically significant. This may suggest that delaying childbirth might be perpetuated and worsen with time in our current society.

#### **2.4. Oocyte donation programmes**

Oocyte donation restores pregnancy possibility in women of advanced reproductive age and reduces the chances for implantation failure found among them. Most women seeking this treatment are happily married women, well-educated and high-income, and physically and psychologically healthy [5]. However, oocyte donation recipients experienced a higher risk of pregnancy complications largely due to advanced maternal age, particularly hypertensive disorders and diabetes, and the risk increases with age [6]. The Ethics Committee of the American Society for Reproductive Medicine recommends women of advanced reproductive age undergo a comprehensive medical test to ascertain fitness for pregnancy in order to prevent the rise of obstetric complications during pregnancy [7]. Multiple pregnancy is known to increase obstetrical and neonatal risks in women of all ages; therefore, it is particularly important to avoid a twin gestation in older mothers.
