January 6, 2009

Birthmarks More Likely Following Prenatal Tests

New research finds that a genetic defect test performed during early pregnancy appears to increase the chances that a baby will be born with an infantile hemangioma, or birthmark.

Chorionic villus sampling, or CVS, which can be performed as early as 10 weeks into pregnancy, uses a needle to collect samples of embryonic material that goes on to form the placenta.  It provides cells of fetal origin that can then be examined for chromosomal defects.

Dr. Lewis B. Holmes of Massachusetts General Hospital for Children, Boston, reviewed published studies to see if the procedure might be linked to infantile hemangiomas, and possibly limb defects, after several previous reports during the 1990s suggested there were sporadic fetal effects from CVS.

"Only a few studies have been conducted on the occurrence of hemangiomas in CVS-exposed infants," Holmes wrote in a report about his analysis.

In one previous study, Holmes wrote, scientists found "cavernous or strawberry hemangiomas" in 12.6 percent of CVS-exposed infants, compared with just 3.4 percent of infants who had been exposed to amniocentesis, which is usually conducted during the later stages of pregnancy.

Another study found hemangiomas in 21.1 percent of 578 CVS-exposed infants, compared with 7.4 percent of 445 amniocentesis-exposed infants. Some in the CVS group had multiple hemangiomas, while none in the amniocentesis group did.

Holmes also reviewed evidence for a link between CVS and birth defects of the limbs, particularly the fingers, and discovered some "clear" associations.  The evidence suggests these risks are higher the earlier in pregnancy the CVS is performed.

Holmes cited one large study that showed that the absence or underdevelopment of any two fingers occurred in 1 of 3,372 CVS-exposed infants, compared with just 1 of 53,751 unexposed infants.

Furthermore, a broad study from 1988 through 1992 found that limb defects were "six times more common in CVS-exposed infants in comparison to the unexposed," wrote Holmes.

However, because CVS detects serious genetic diseases such as Down's Syndrome, "the benefits of knowing the test results could outweigh the possible risk of hemangiomas or other abnormalities," wrote the editor of the Journal of Craniofacial Surgery.

Holmes' report was published in the December 2008 Journal of Craniofacial Surgery.


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