Mother’s age

Older women face a higher risk of bad chromosomes than younger women.  Among women who have miscarried, about 36% of 24-year-old patients had chromosome abnormalities, but for 35-year-old patients, the number was 68%.

Likelihood of Miscarriage with Chromosome Abnormalities by Maternal Age

The pregnancy’s time of demise

Earlier losses are more likely to have chromosome abnormalities than later losses.  Before assuming irregular chromosomes, you need to know the pregnancy’s time of demise, (The time of demise is when the pregnancy actually stopped developing, and can be several weeks before the bleeding and cramping of miscarriage actually occur. Some women’s bodies take weeks to realize that the pregnancy has stopped growing, thus their bodies make no attempt to miscarry.  Time of demise can be estimated with ultrasound.) which can occur weeks before the bleeding and cramping of miscarriage.

Estimated Chance of Miscarriage with Chromosome Abnormalities by Time of Demise