Causes of Fetal WastageSIMPSON, JOE LEIGH MDClinical Obstetrics & Gynecology: March 2007 - Volume 50 - Issue 1 - pp 10-30 doi: 10.1097/GRF.0b013e31802f11f6 First Trimester Pregnancy Complications Abstract Author Information Fetal wastage has many causes, but genetic factors are by far the most common. The earlier the pregnancy loss occurs, the greater the likelihood of genetic causation. Among first trimester abortions, 50% to 80% show chromosomal abnormalities, usually aneuploidy. This is greater than all other causes combined. Chromosomal numerical abnormalities can be recurrent and sporadic; failure to take this into account is a major pitfall in many reports addressing causation. Moreover, many causes of fetal wastage that are traditionally considered to be “nongenetic” are actually the result of perturbations of gene products-proteins. Among nongenetic causes of first trimester fetal wastage, the best established are thyroid abnormities; antifetal antibodies; and the inherited and acquired thrombophilias. The latter are more established in the second trimester. Uterine anomalies can lead to second trimester losses. Infections seem uncommon, and alloimmune causes are not validated. Departments of Obstetrics and Gynecology; and Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas Correspondence: Joe Leigh Simpson, MD, Departments of Obstetrics and Gynecology; and Molecular and Human Genetics, Baylor College of Medicine, 1709 Dryden Rd, Suite 1100, Houston, TX 77030. E-mail: firstname.lastname@example.org © 2007 Lippincott Williams & Wilkins, Inc.