What are some common reasons for miscarriage?

Advanced maternal age is a well-documented risk factor for miscarriage. As women age, particularly beyond the age of 35, the quality and viability of the oocytes (eggs) decline, leading to an increased likelihood of chromosomal abnormalities in the embryo. These abnormalities are a major cause of miscarriage, as the body often recognizes these non-viable embryos and terminates the pregnancy.

When considering the other factors listed, low maternal age is generally associated with a lower risk of miscarriage due to better oocyte quality and overall reproductive health. Multiple pregnancies can carry their own risks but do not directly correlate with increased miscarriage in the same way that advanced maternal age does. The absence of maternal smoking is a protective factor for pregnancy outcomes, but it is not a reason for miscarriage; conversely, smoking is linked to higher miscarriage rates. Therefore, advanced maternal age stands out as the primary reason for the increased incidence of miscarriage in women.