Risks And Benefits Of Genetic Testing If You're Carrying Twins

7 October 2015
 Categories: , Blog

Genetic testing during pregnancy is a way to screen for potential birth defects.  While the procedures can provide useful information, they come with certain risks, especially if you're carrying twins.  This article looks at some of the pros and cons of genetic testing when you're expecting more than one baby.

What Tests Are Available

There are two main genetic tests available during pregnancy: amniocentesis and chorionic villus sampling (CVS). During amniocentesis the OBGYN collects a small amount of the amniotic fluid.  During CVS, the small chorionic villus projections that line the placenta are collected.  In both cases the samples are used to create a karyotype describing the baby's chromosomes.  It is then possible to identify chromosomal disorders such as Down's Syndrome and Turner Syndrome, as well as genetic disorders such as cystic fibrosis and Tay-Sachs. 

Twins and Genetic Disorders

Simply being a twin doesn't affect a baby's DNA, so there isn't an inherent increased risk for genetic disorders simply because you are carrying multiples.  However, because each baby has it's own risk, when there is more than one baby, there is an overall greater likelihood of a disorder, especially if there are other contributing factors such as maternal age or family history.  Having multiples is a challenge in itself.  Finding out early if there may be additional struggles can help a family prepare emotionally and give them time to arrange for extra support after the births.  On the other hand, if the results are negative, being able to rule out genetic disorders can help reduce anxiety during an already stressful pregnancy. 

Unexpected Benefit

Besides telling you if the babies have a genetic disorder, genetic testing can also provide another interesting piece of information.  Because identical twins have the same DNA, genetic testing can tell you if you are expecting identical or fraternal twins.


Even when twins aren't involved, genetic testing procedures such as amniocentesis and CVS are invasive and involve risks.  Carrying twins further complicates the situation.  First, accuracy can be difficult, because the technician must be very careful to collect samples from each baby without getting anything mixed up--a tricky task with two moving babies!  Second, and more importantly, the risk for miscarriage is significantly higher for twins.  For example, with amniocentesis, approximately 3.5% of twins will miscarry following the procedure.  The miscarriage rate for CVS may be higher, around 4%.  

Deciding to receive genetic testing during a pregnancy can help a family have peace of mind or give them time to prepare for upcoming challenges.  These benefits have to be carefully balanced against the risks, especially with twins.  Use the information in this article to help decide if these procedures are right for your pregnancy. For more advice, contact a clinic such as Contemporary Health Care for Women.