New genetic test assures healthy pregnancy

Couples undergoing In Vitro Fertilisation (IVF) can now celebrate as a new revolutionary technology allows detection of genetic abnormalities that are even too small to be detected by looking down the microscope. Infertility experts are vouching for the latest technology called ‘Array CGH’, which has a predicted accuracy of 98 per cent for detecting chromosome abnormalities.

Dr Lakshmi Chirumamilla, senior fertility consultant, Nova IVI Fertility, Hyderabad, says, “Chromosomal or genetic screening can help prevent chromosomal abnormalities most commonly seen in women opting for pregnancy at an advanced age of 38 or more, those suffering from recurrent implantation failure (five or more embryos have been replaced without success), history of recurrent miscarriage or with a previous pregnancy with a chromosome error such as down syndrome or severe male factor infertility.”

Chromosomal abnormalities are responsible for about 70 per cent of miscarriages in early pregnancy. They are very common in eggs and embryos. The risk of having an embryo with the wrong number of chromosomes is greatly affected by the age of the mother. For women in their early thirties about one quarter of the eggs and embryos have an abnormal number of chromosomes, but for women over 40 it is usual for more than half of the embryos produced to be abnormal.

D Lakshmi says, “Traditionally used karyotyping is only as good as the resolution of the microscope and is not able to detect subtle chromosome changes. These smaller alterations, often called submicroscopic alterations cannot be seen down the microscope, but can still disrupt growth and development.”

In Array CGH, a single cell is biopsied (removed) from the embryo on day three of development in the laboratory, and the DNA from the cell’s nucleus is multiplied thousands of times before being placed on a microarray, or DNA chip, where it is compared with normal male and female DNA. Moreover, array CGH can be done on both eggs and embryos and offers much more precise information.

This allows accurate detection of chromosome errors, increasing the chance of a healthy baby resulting from the transfer of a chromosomally normal embryo. “We at Nova IVI Fertility are the pioneers to use Array CGH technology in India. The main advantage of this technology is that only chromosomally normal embryos are transferred for a successful delivery. It increases the implantation and ongoing pregnancy rate for IVF patients.

Moreover, single embryo transfer to reduce multiple pregnancies, reduces the time to pregnancy, lowers the incidence for miscarriage and most importantly reduces the risk of abnormalities at birth,” added Dr Lakshmi. Using advanced embryo selection, testing can be performed on a single cell from a day three embyro, whereas similar forms of technology require embryos to develop to the blastocyst stage on day five in order for several cells to be available for testing.

Array CGH is not just accurate, but it is faster too. It provides accurate results within 30 hours, meaning patients can undertake a fresh embryo transfer, and their treatment can continue uninterrupted, whereas in most cases embryos that need to be biopsied on day five must be frozen because the results are not available in time to perform a fresh embryo transfer.