Unfortunately, as women age, there is a natural decline in fertility due to depletion of ovarian reserve and lower egg quality. We also observe a higher rate of abnormalities in the egg resulting in aneuploid embryos if fertilization takes place. Aneuploidy is an abnormal distribution of chromosomes in the egg that can result in disorders such as trisomy 21, or Down Syndrome. 

Dissimilar to women, men do not experience the same age-related effects on fertility. Women are essentially infertile by their mid 40s, whereas men become subfertile around their mid 40s due to declining sperm motility and morphology.