All are true about aneuploidy except:
30% of trisomy 21 fetus die in utero
80% of trisomy 18 fetus die in uero
Occurrence of aneuploidy has no relation with the progression of mother's age
The recurrence risk for nondysjunctional aneuploidy is 1% higher
Aneuploidy

Each human cell consists of 23 pair of chromosomes i.e., the normal chromosome number is 46
Aneuploidy is a deviation from the normal number of 46 chromosome. Which could be be 47 or 45 chromosomes or it can be defined as state of having chromosome number that is not multiple of 23.

Nondisjunction

Nondisjunction is failure of paired homologus chromosomes to separate during the first meiotic division that leads to the production of gametes (ova and spermatozoa).
Thus, some gametes receive two and other receive none of the involved pair. After the second meiotic division the resulting gametes will have 24 and 22 chromosomes respectively. Such gametes are aneuploid.

Anaphase lag

In anaphase lag, one homologus chromosome in meiosis or one chromatid in mitosis lags behind and is left out of the cell nucleus. This results in one normal cell and one cell with monosomy.

Survival of Aneuploidy

Monosomy or trisomy involving the sex chromosome are compatible with life and are usually associated with variable degree of phenotypic abnormalities.
Monosomy involving an autosome generally represents loss of too much genetic information to permit live births or  even embryogenesis.
With the exception of trisomy 21 all others will produce severely handicapped infants who almost invariably die at an early age.

Estimated abortion rate in early pregnancy