Many of Your Best Embryos are Chromosomally Abnormal Studies from many different IVF clinics have shown that even embryos with good physical appearance or "morphology" can have chromosome problems. Even in women younger than 35, at least one third of the embryos have abnormal numbers of chromosomes. The number of embryos that have abnormal chromosomes increases every year since eggs become older.	Photo Slideshow: A Look Inside IVF
A technique called Preimplantation Genetic Diagnostics or PGD can select most of those embryos that are chromosomally normal so that they are transferred to your uterus. This can improve the chance of getting pregnant and carrying to term. And can reduce the chance of having a baby with a condition like Down syndrome. It also may decrease the chance of losing a pregnancy early.

What are Chromosomes?
Chromosomes are string-like structures found in the center of every cell (the nucleus). Chromosomes contain genes that are made of DNA. Therefore, out inherited information is housed on the chromosomes. Normal human cells (embryo, fetus, baby or adult) contain 46 Chromosomes or 23 pairs. We receive 23 chromosomes from each parent. The first 22 pairs of are the same for men and women and labeled largest to smallest: 1 through 22. The 23 rd pair determines our sex. To test for a chromosome abnormality such as Down syndrome, the chromosomes are studied.

Chromosomal Aneuploidy
Spermatozoa or eggs that have extra or missing chromosomes will pass this problem on to the embryo after fertilization. This situation is known as aneuploidy. There can be extra (trisomy) or missing (monosomy) chromosomes. Both conditions are a problem. If the aneuploidy involves the larger chromosomes, the embryo may not attach to the wall of the uterus or may stop developing soon after and miscarry. In some cases, however, the aneuploidy may cause the fetus to be abnormal but carry to birth. Down syndrome is an example of this, but there are several other types. The features of the chromosome condition depend upon which chromosome is extra or missing, but can include physical abnormalities and mental retardation.

Risk of Aneuploidy and Maternal Age
As a woman advances in age, the chance of aneuploidy in her pregnancies increases. This association is due to the fact that a woman's eggs are as old as she is. Females have all of their eggs from the fetal stage on, therefore they are born with all the eggs they will have in their lifetime. As such, the theory regarding aneuploidy risk and advancing maternal age is that, over time, the chromosomes in the egg are less likely to divide properly leading to the egg having an extra or missing chromosome. The risk of conceiving an abnormal baby increases with maternal age, but the frequency of aneuploidy in embryos is much higher than at delivery. This difference in percentages of affected embryos versus live born is due to the fact that a pregnancy with aneuploidy is less likely to attach to the uterus or go to term. Most will not implant or will be miscarried. The percentage of affected pregnancies is reduced over the course of the pregnancy. The lack of implantation and loss rate of aneuploidy embryos are believed to be the main reasons why pregnancy rates decrease with advancing maternal age.

Avoiding Transfer of Chromosomally Abnormal Embryos
Aneuploid embryos are mostly indistinguishable morphologically and developmentally from chromosomally normal ones, thus, without genetically testing them, the embryologists doing your IVF procedure cannot recognize them and may transfer chromosomally abnormal embryos to you.

The PGD Procedure
Thankfully, in the last 10 years a technique called Preimplantation Genetic Diagnostics (PGD) has been developed to test your embryos prior to the transfer of the embryos to the uterus. This technique consists of the removal (biopsy) of one cell of each embryo, followed by a very fast genetic analysis using a technique called fluorescence in situ hybridization (FISH), and the subsequent replacement of those embryos identified as normal. Normal embryos have a higher chance of implanting, resulting in pregnancy and not miscarrying, than abnormal embryos.

Learn More About the PGD Procedure

An embryo undergoing blastomere (single cell) removal
in order to diagnose the genetic make-up of the embryo

Advantages of the PGD Procedure
Most chromosomally abnormal embryos either do not implant or spontaneously abort shortly after implantation. Thus, if only normal embryos are replaced, which have higher chances of implanting and reaching term, the probability of conceiving a healthy child may increase if PGD is applied.

PGD of aneuploidy has been proven to double implantation rates in several studies, reduce the rate of pregnancy loss by half and increase take-home baby rates. Unpublished data from Reprogenetics also indicate a four-fold reduction in the frequency of chromosomally abnormal conceptions after PGD.

	Women 37 and older: Any IVF patient 27 years of age or older can benefit from PGD, provided that they produce 5 or more embryos. It is possible that women 35-37 may also benefit from the procedure.
	Women with a prior history of multiple miscarriage or aneuploid pregnancies: Regardless of age, these patients could benefit from PGD. In all these patients, higher implantation rates, reduced pregnancy loss and reduced risk of chromosomally abnormal conceptions are expected after PGD. It is not clear yet if patients with repeated IVF failure benefit from PGD.
	Patients with a chromosome condition: Individuals with certain chromosome conditions can reduce their chance of passing the condition to their child via PGD.
	Severe male infertility: A high rate of chromosome abnormalities has been seen in embryos from men with non-obstructive azoospermia. PGD may also be indicated for other cases of very severe male infertility.

How Can You Have PGD?
PGD is usually preformed in a very specialized genetics center. Your IVF center will arrange for or perform the biopsy and process the cell and then send it to Reprogenetics. Reprogenetics scientists developed the first tests for PGD of aneuploidy, and therefore, are one of the PGD centers with the most experience in this technique. For more information regarding Reprogenetics, please check www.reprogenetics.com. If you are interested in PGD, please contact your physician at your IVF center.

What About Cost?
As you might expect, this technology doesn't come cheaply. This procedure may add close to $5,000 to the cost of IVF. Few insurance policies cover the expense.