May 18, 2015

What are Chromosomes?

Chromosomes and IVF

How Do Chromosomes Affect My Chance of a Successful Pregnancy?

The excitement of learning you’re pregnant is often met with anxiety of the unknown. Questions about your baby’s health and development may start to overwhelm you. An abnormal number of chromosomes is often at the heart of many of the fear-inducing issues you will face. Fortunately, there is a way to avoid most this anxiety so you can focus on all the wonderful aspects of pregnancy.

The Fertility Centers of New England is proud to introduce IVF Assist Plus, the most innovative money-back guarantee program available to give you a baby with the correct number of chromosomes, which will assure the highest chance of a successful pregnancy.

What are Chromosomes and Why are They Important?

In the nucleus of each cell, the DNA molecule is packaged into these thread-like structures we call chromosomes. Genes are located on chromosomes that are passed from parent to child, making each of us unique. In other words, chromosomes make you, you. Having the right number of chromosomes is critically important to having a successful pregnancy. If your embryo does not have the correct number of chromosomes then your baby may fail to develop properly. For example, people with Down syndrome have three copies of chromosome 21 (Trisomy 21) instead of the two copies found in other people.

People have 23 pairs of chromosomes for a total of 46 chromosomes. Males and females differ in a pair of chromosomes called sex chromosomes. As you probably know, females have two X chromosomes in their cells and males have one X and one Y chromosome. Inheriting too many or not enough sex chromosomes can lead to serious problems. For example females who have extra copies of the X chromosome are usually taller than average and have mental handicaps. Males with more than one X chromosome have Klinefelter syndrome which is a condition characterized by tall stature and often infertility. Another syndrome caused by imbalance in the number of sex chromosomes is Turner syndrome. Women with Turner syndrome have only one X chromosome. They are usually very short, do not undergo puberty and some have kidney and heart problems.

How can Fertility Centers of New England Help?

The statistics can be daunting: for most women under age 35 the chance of becoming pregnant is only 20% per natural cycle attempt. Of those that are able to become pregnant, 15% of pregnancies end in a miscarriage. The chance of a successful pregnancy in a woman with infertility who is under age 35 may be as high as 50% following IVF. However the chance of multiples (twins or greater) in these same women is as high as 30% if two or more embryos are transferred.

How can we overcome some of these statistics? At Fertility Centers of New England, we can help ease the fears of the challenges that abnormal chromosomes can bring. Pre-Implantation Genetic Screening (PGS) allows for an elective single embryo transfer (eSET). This is important because the chance of pregnancy is as high as 70% following transfer of a single embryo with the correct number of chromosomes. Preimplantation genetic screening (PGS) of a cell biopsied from an embryo can improve the chance of a successful pregnancy by determining which embryo has the correct number of chromosomes. This enables the transfer of that embryo, instead of an embryo that does not have the correct number of chromosomes and thus would be less likely to make a healthy baby. This technology is particularly applicable to couples with infertility who have an otherwise poor prognosis for success due to advanced maternal age. The older a woman is the more likely she is to have an abnormal embryo or who have repeated implantation failure following IVF, and in women with recurrent miscarriage, since most miscarriages are caused by an incorrect number of chromosomes.

PGS allows all 23 pairs of chromosomes (22 pairs of autosomal chromosomes and the pair of chromosomes that defines genetic sex). This screening allows us to identify normal chromosomes that may exist in embryos produced during an IVF cycle. Usually there is no guarantee that each IVF cycle is going to generate a normal embryo. However, Fertility Centers of New England ’s exclusive IVF Assist Plus program virtually eliminates the chances of a baby being born with a chromosome abnormality once the embryo has been determined to have the correct number of chromosomes by PGS.

If you have more questions or would like to schedule a consult, please contact us!

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Joseph A. Hill, III, M.D.

Joseph A. Hill, III, M.D. Board-Certified in Reproductive Endocrinology and Infertility