There are many different reasons for having a miscarriage but the actual reasons for the miscarriage is often unknown. Approximately 50% of first trimester miscarriages are due to a chromosome abnormality in the fetus, though some people believe the incidence is higher than 50%. The most common chromosomal cause of a miscarriage before 12 weeks is an abnormality such as

  • Monosomy X,
  • trisomy 16,
  • trisomy 21,
  • trisomy 13, and
  • trisomy 18.

Most chromosomal abnormalities are the cause of a faulty egg or sperm cell, or are due to a problem at the time that the zygote went through the division process.Occasionally a miscarriage can be caused by an inherited variation with the chromosomes. For example, a parent can have a rearrangement (a "translocation") of his or her chromosomes, in which the chromosomes are structured differently.

Causes for miscarriage include:

  • Chromosomal anomalies
  • Maternal age
  • Infections 
  • Maternal health problems
  • Smoking, 
  • Drug use, 
  • Malnutrition
  • Exposure to radiation or toxic substances
  • Maternal trauma
  • Cervical incompetence (insufficiency)

Return to Miscarriage overview

Keyword Tags: