| The vast majority of IVF babies are born normal and | | | | missing pairs or have one extra copy. PGD can test |
| grow up healthy. While the IVF risk for genetic | | | | several chromosomes for disorders, but not all 23 |
| defects is small, it increases with the age of the | | | | pairs. Another issue with PGD is that it can be |
| mother. | | | | inaccurate. There have been instances where healthy |
| The good news is that genetic defects in IVF-born | | | | embryos have been considered abnormal by PGD or |
| babies can, for the most part, be prevented through | | | | where abnormal embryos were considered healthy. |
| the help of embryo screening techniques. Embryo | | | | This is also the result of the test's limitations - even if |
| screening looks at a cell sample of an embryo for the | | | | one cell is tested normal, there is a chance that the |
| presence of chromosomal abnormalities that carry | | | | other untested cells may have undetected abnormal |
| genetic disorders like Beckwith-Widemann Syndrome, | | | | chromosomes. Comparative genomic hybridisation |
| Down 's syndrome, even certain types of cancer. It | | | | (CGH) |
| is not a perfect process and it cannot detect all | | | | A new approach called comparative genomic |
| conditions, but if you are over 35 and considering | | | | hybridization (CGH) can be added to a PGD |
| IVF, embryo screening is something to seriously | | | | procedure for more accurate results. It is more |
| consider. Pre-implantation genetic diagnosis (PGD) to | | | | difficult to perform and takes longer to complete but |
| Reduce Risk | | | | unlike a standard PGD, a CGH can identify genetic |
| Pre-implantation genetic diagnosis (PGD) was first | | | | disorders in all 23 chromosomes. Like in a standard |
| introduced to the public in 1987 to help couples avoid | | | | PGD, a blastomere is collected from the cell during cell |
| embryos with a particular genetic disorder. PGD was | | | | division. Before examining the cell for genetic |
| initially restricted to those couples who are carriers of | | | | conditions, a labeled identical copy of each |
| a potentially-life threatening genetic condition, but | | | | chromosome found in the cell is made. These DNA |
| most clinics now offer the procedure to anyone who | | | | copies are then matched up or hybridized with labeled |
| wants to avail of it. IVF patients who are older than | | | | copies of DNA from a different but normal cell. The |
| 38, and who have had subsequent miscarriages or | | | | sample DNA and normal DHA are each labeled by |
| failed IVF cycles can benefit from PGD. | | | | certain colors, which are then analyzed by a |
| PGD is typically performed after fertilization, when | | | | computer program. Test cells that contain the normal |
| the embryos are anywhere between the four and | | | | number of chromosomes have the same color |
| ten-cell developmental stage. A single blastomere | | | | intensity as the normal cell. Test cells with too many |
| (cell) or two is gently removed from the embryo | | | | chromosomes have a higher color intensity, while test |
| using nanosurgical techniques, and analyzed for the | | | | cells with too few chromosomes have a lighter color |
| presence of specific conditions. Only embryos without | | | | intensity. |
| these disorders are transferred into the uterus. Aside | | | | Small clinical trials suggest that CGH can increase the |
| from guaranteeing the health of your baby, PGD also | | | | success of IVF by about 25%. Make an informed |
| increases the chances of carrying a pregnancy to | | | | decision About IVF Risks |
| term because it filters out embryos with an abnormal | | | | These approaches are very useful and they can |
| number of chromosomes. Chromosomal abnormalities | | | | increase your chance of a successful IVF. However, |
| are the leading cause of miscarriages because they | | | | keep in mind that they do not absolutely guarantee |
| are unable to implant and develop normally. | | | | accurate results. There is a slim chance that genetic |
| Even though PGD can be used to identify a number | | | | defects and abnormalities can occur in babies with |
| of disorders, it cannot identify every single one. A | | | | normal karyotypes, or chromosome profile. Do your |
| normal, healthy embryo has 23 chromosome pairs, | | | | research carefully and think about whether these |
| and certain disorders like aneuploidy may have | | | | promising procedures are the best route for you. |