Maternal age

The risk for trisomies 18 and 13 increases with maternal age and decreases with gestation. The rate of fetal death between the 12th and 40th week is about 80%.

Turner syndrome is unrelated to maternal age. The rate of fetal death between the 12th and 40th week is about 80%. The prevalence is about 1 in 1500 at 12 weeks and 1 in 4000 at 40 weeks.

Triploidy is unrelated to maternal age. The prevalence at 12 weeks is about 1 in 2000 but it is highly lethal and is very rarely observed in live births.