PreImplantation Genetic Diagnosis Improves Pregnancy Rates
The Pre-implantation genetic diagnosis (PGD) analyses embryos to determine whether they carry genetic based diseases before transferring them to the womb. This enables the implantation of healthy embryos only.
ProcreaTec Fertility Center’s last year’s statistics reveal how the Preimplantation Genetic Diagnosis can improve success rates. In 2018, the pregnancy rate of women ages 35-39 undergoing an IVF treatment with their own eggs was 47.2% without PGD and using this genetic diagnosis, it improved to 67%. In women over 40, the rate increase was even more dramatic, going from a 15.4% success rate to 50% when using PGD. As Dr. López Yáñez explains, “it is not only about improving the pregnancy rate, but it is also about achieving the pregnancy goal sooner”.
In the egg donation treatment, the use of PGD is also notable. The pregnancy rate for a single embryo transfer (SET) in 2018 in the first transfer was 60%, and 75.6% in double embryo transfers (DET). When performing PGD, the pregnancy rate in the egg donation treatment was 71.4% in SET, almost the same success rate as when transferring two without PGD, but avoiding the risk of a multiple pregnancy.
When is PGD recommended?
PGD diagnoses if embryos are carriers of a chromosomic alteration inherited from the parents. It allows us to choose a healthy embryo or an embryo not carrying a disease before transferring it into the uterus. It is indicated to couples who has been diagnosed with a genetic disease, such as Huntington’s disease or Cystic Fibrosis. It could also let us know the baby’s gender, but in Spain that choice is only legal when it comes to a genetic disease associated to gender.
Preimplantation Genetic Screening studies the number of chromosomes each embryo has for the purpose of transferring only healthy embryos, as an alteration of the number can be a reason for implantation failure or miscarriage. This technique is indicated in the following cases:
- Implantation failures
- Recurrent miscarriages
- Patient with more than 40 years who is going to undergo an IVF cycle
- Altered FISH results in sperm
- Known inherited genetic diseases
PGD can be divided into two types:
· PGD for the analysis of monogenic or inherited diseases and for structural chromosomic alterations. In this case, a preliminary workup prior to the treatment may have to be done in order to carry out the diagnosis correctly.
· PGS or aneuploidy screening consists in the analysis of the number of copies of the chromosomes. It is indicated in women of advanced maternal age, recurrent miscarriages, repeated implantation failures in previous cycles, or FISH in altered spermatozoa.
How is a treatment with PGD carried out?
The PGD process can be part of the IVF treatment with the women’s own eggs as well as with donated eggs. The stimulation (of either the patient or the donor) is carried out as usual, and the eggs are fertilized in the laboratory. When performing PGD, the only difference is that with the embryo(s) that result from fertilization are biopsied. In this embryo biopsy, a few embryo cells are collected and analysed to check whether the embryo carries a genetic defect. Affected embryos will be discarded and only the healthy ones will be eligible for selection to be transferred to the womb.
We have to take into consideration that these techniques are increasing success rates of women with the said medical record, but they do not guarantee that embryos are not carriers of other malformations or genetic diseases.
PGD is a complementary technique used in IVF and egg donation treatments. We recommend receiving a personalised assessment from one of our doctors as to what the most appropriate treatment and technique for you. You can request a free appointment on our website en.procreatec.com